Fix: authorize document versions by their root in the single-object permission check

has_perms_owner_aware judged a document by its own owner and grants, so each
endpoint that fetches a document itself had to remember to map a version to
its root document first, and one that forgot, like the more-like-this search
filter, authorized by a stale version owner.

The check now maps a Document to its root before looking at the owner and the
guardian grants, matching what permitted_document_ids does for id sets. The
eight call sites that mapped the document themselves pass it straight through.
The DRF object permission class needs no change because the document viewset
only ever serves root documents.

src/documents/permissions.py

@@ -6,7 +6,9 @@ from django.contrib.auth.models import Permission
 from django.contrib.auth.models import User
 from django.contrib.contenttypes.models import ContentType
 from django.db.models import Case
+from django.db.models import CharField
 from django.db.models import Count
+from django.db.models import F
 from django.db.models import IntegerField
 from django.db.models import Model
 from django.db.models import Q
@@ -26,6 +28,7 @@ from rest_framework.permissions import BasePermission
 from rest_framework.permissions import DjangoObjectPermissions
 
 from documents.models import Document
+from documents.versioning import get_root_document
 
 
 class PaperlessObjectPermissions(DjangoObjectPermissions):
@@ -349,6 +352,7 @@ def permitted_object_ids(
     perm: str,
     *,
     include_deleted: bool = False,
+    parent_field: str | None = None,
 ) -> QuerySet[int]:
     """
     Generic version of ``permitted_document_ids`` for any model with an
@@ -357,6 +361,24 @@ def permitted_object_ids(
     soft-delete pattern (currently only ``Document``); for every other model
     it is accepted but has no effect, since those models have no soft-delete
     concept.
+
+    ``parent_field`` names a self-referencing foreign key whose target
+    authorizes the row (``Document.root_document``). A row with a parent is
+    visible exactly when its parent is, judged by the parent's owner and
+    grants, so the row's own owner and grants are ignored.
+
+    Guardian stores ``object_pk`` as a string, so the row key is cast to a
+    string and tested against the user's and groups' grants with a single
+    uncorrelated ``IN``. Postgres and SQLite build that set once. MariaDB
+    evaluates it as an index probe per row, which is cheap because the
+    lookups use guardian's unique indexes. Casting every ``object_pk`` to an
+    integer instead cannot use an index, and MariaDB cannot materialize it
+    inside the owner ``OR``, so it re-scans the user's grants for every row.
+    A correlated ``EXISTS`` per grant fixes MariaDB too, but Postgres and
+    SQLite re-run it for every row and end up slower than the original. The
+    user's groups are matched with an ``IN`` subquery rather than a join
+    through the membership table, which SQLite plans badly once the grant
+    tables grow.
     """
     has_soft_delete = hasattr(model, "global_objects")
     manager = (
@@ -364,8 +386,21 @@ def permitted_object_ids(
     )
     base_qs = manager.all().only("id", "owner")
 
+    owner_field, key_field = "owner", "pk"
+    if parent_field is not None:
+        owner_field, key_field = "authorizing_owner", "authorizing_id"
+        base_qs = base_qs.annotate(
+            authorizing_id=Coalesce(f"{parent_field}_id", "id"),
+            authorizing_owner=Case(
+                When(**{f"{parent_field}_id__isnull": True}, then=F("owner_id")),
+                default=F(f"{parent_field}__owner_id"),
+                output_field=IntegerField(),
+            ),
+        )
+    unowned = Q(**{f"{owner_field}__isnull": True})
+
     if user is None or not getattr(user, "is_authenticated", False):
-        return base_qs.filter(owner__isnull=True).values_list("id", flat=True)
+        return base_qs.filter(unowned).values_list("id", flat=True)
 
     # Deactivated users get nothing, deactivated superusers included, so this
     # has to come before the superuser shortcut. guardian's
@@ -389,21 +424,26 @@ def permitted_object_ids(
         "permission__content_type": content_type,
     }
 
-    user_perm_ids = (
-        UserObjectPermission.objects.filter(user=user, **perm_filter)
-        .annotate(object_pk_int=Cast("object_pk", IntegerField()))
-        .values_list("object_pk_int", flat=True)
-    )
-    group_perm_ids = (
-        GroupObjectPermission.objects.filter(group__user=user, **perm_filter)
-        .annotate(object_pk_int=Cast("object_pk", IntegerField()))
-        .values_list("object_pk_int", flat=True)
-    )
-    permitted_ids = user_perm_ids.union(group_perm_ids)
+    # Both grant sets are compared to the row key as strings, exactly as
+    # guardian stores them, and are uncorrelated, so each engine can build the
+    # set once instead of probing per row.
+    user_keys = UserObjectPermission.objects.filter(
+        user=user,
+        **perm_filter,
+    ).values_list("object_pk", flat=True)
+    group_keys = GroupObjectPermission.objects.filter(
+        group_id__in=user.groups.values("id"),
+        **perm_filter,
+    ).values_list("object_pk", flat=True)
+    permitted_keys = user_keys.union(group_keys, all=True)
 
-    return base_qs.filter(
-        Q(owner=user) | Q(owner__isnull=True) | Q(id__in=permitted_ids),
-    ).values_list("id", flat=True)
+    return (
+        base_qs.annotate(permitted_key=Cast(key_field, CharField(max_length=64)))
+        .filter(
+            Q(**{owner_field: user.pk}) | unowned | Q(permitted_key__in=permitted_keys),
+        )
+        .values_list("id", flat=True)
+    )
 
 
 ModelT = TypeVar("ModelT", bound=Model)
@@ -471,30 +511,16 @@ def permitted_document_ids(
     ``include_deleted=True`` for callers that need to check permission on
     soft-deleted documents (e.g. trash restore). This intentionally avoids
     ``get_objects_for_user`` to keep the subquery small and index-friendly.
-    """
-    return permitted_object_ids(user, Document, perm, include_deleted=include_deleted)
 
-
-def documents_without_permitted_root(
-    documents: QuerySet[Document],
-    user: User | None,
-    *,
-    perm: str = "view_document",
-    include_deleted: bool = False,
-) -> QuerySet[Document]:
+    A version is authorized by its root document, so a version's own owner and
+    grants never matter.
     """
-    The documents the user lacks ``perm`` on. Versions are authorized by their
-    root document, so a version's own owner is ignored. A single query, without
-    loading the documents or joining the root.
-    """
-    return documents.annotate(
-        root_id=Coalesce("root_document_id", "id"),
-    ).exclude(
-        root_id__in=permitted_document_ids(
-            user,
-            perm=perm,
-            include_deleted=include_deleted,
-        ),
+    return permitted_object_ids(
+        user,
+        Document,
+        perm,
+        include_deleted=include_deleted,
+        parent_field="root_document",
     )
 
 
@@ -654,7 +680,14 @@ def has_perms_owner_aware(user, perms, obj):
     single-object check still has many production callers. Several callers
     remain across ``documents/``, ``paperless_mail/``, and ``paperless_ai/``
     -- grep for this function name before removing it.
+
+    A document version is authorized by its root document, like in
+    ``permitted_document_ids``, so a version's own owner and grants never
+    matter. Fetch the root with ``select_related("root_document__owner")`` to
+    avoid extra queries.
     """
+    if isinstance(obj, Document):
+        obj = get_root_document(obj)
     checker = ObjectPermissionChecker(user)
     return obj.owner is None or obj.owner == user or checker.has_perm(perms, obj)
 

src/documents/serialisers.py

@@ -90,7 +90,6 @@ from documents.templating.utils import convert_format_str_to_template_format
 from documents.templating.workflows import validate_workflow_template
 from documents.validators import uri_validator
 from documents.validators import url_validator
-from documents.versioning import get_root_document
 from documents.versioning import has_prefetched_effective_content
 from documents.versioning import sort_versions_newest_first
 
@@ -2895,7 +2894,7 @@ class ShareLinkSerializer(OwnedObjectSerializer):
             and has_perms_owner_aware(
                 self.user,
                 "view_document",
-                get_root_document(document),
+                document,
             )
         ):
             return document

src/documents/tests/test_permission_filtering_security.py

@@ -18,6 +18,7 @@ from documents.models import Correspondent
 from documents.models import DocumentType
 from documents.models import StoragePath
 from documents.models import Tag
+from documents.permissions import has_perms_owner_aware
 from documents.permissions import permitted_document_ids
 from documents.permissions import permitted_object_ids
 from documents.permissions import restrict_queryset_to_visible
@@ -32,6 +33,8 @@ from paperless_testing.permissions import grant_global
 from paperless_testing.permissions import grant_object
 
 if TYPE_CHECKING:
+    from django.contrib.auth.models import User
+
     from paperless_testing.dirs import PaperlessDirs
 
 
@@ -178,6 +181,382 @@ class TestPermittedDocumentIdsIncludeDeleted:
         )
 
 
+@pytest.mark.django_db
+class TestPermittedDocumentIdsVersions:
+    """
+    A version is authorized by its root document: the version's own owner and
+    grants never matter.
+    """
+
+    @pytest.mark.parametrize(
+        ("root_owner", "version_owner", "expected_visible"),
+        [
+            pytest.param(
+                "other",
+                "nobody",
+                False,
+                id="unowned-version-of-private-root",
+            ),
+            pytest.param("other", "user", False, id="own-version-of-private-root"),
+            pytest.param("user", "other", True, id="foreign-version-of-own-root"),
+            pytest.param("user", "nobody", True, id="unowned-version-of-own-root"),
+            pytest.param("nobody", "other", True, id="private-version-of-unowned-root"),
+        ],
+    )
+    def test_version_follows_root_owner(
+        self,
+        root_owner: str,
+        version_owner: str,
+        *,
+        expected_visible: bool,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document and a version with differing owners
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - The version is visible exactly when its root is
+        """
+        user = UserFactory()
+        owners = {"user": user, "other": UserFactory(), "nobody": None}
+        root = DocumentFactory(owner=owners[root_owner])
+        version = DocumentFactory(root_document=root, owner=owners[version_owner])
+
+        visible = set(permitted_document_ids(user))
+
+        assert (version.pk in visible) is expected_visible
+        assert (root.pk in visible) is expected_visible
+
+    @staticmethod
+    def grantee(user: User, kind: str) -> User | Group:
+        """The user itself, or a new group the user belongs to."""
+        if kind == "user":
+            return user
+        group = Group.objects.create(name="shared")
+        user.groups.add(group)
+        return group
+
+    @pytest.mark.parametrize(
+        "grantee_kind",
+        [pytest.param("user", id="user"), pytest.param("group", id="group")],
+    )
+    def test_grant_on_root_applies_to_version(self, grantee_kind: str) -> None:
+        """
+        GIVEN:
+            - A private root document shared with a user or one of their groups
+            - A version of it owned by someone else
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Both the root and the version are visible
+            - A user without the grant sees neither
+        """
+        user = UserFactory()
+        stranger = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(self.grantee(user, grantee_kind), root, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+        assert_visible_document_ids(
+            permitted_document_ids(stranger),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    @pytest.mark.parametrize(
+        "grantee_kind",
+        [pytest.param("user", id="user"), pytest.param("group", id="group")],
+    )
+    def test_grant_on_version_is_ignored(self, grantee_kind: str) -> None:
+        """
+        GIVEN:
+            - A private root document
+            - A version with an explicit grant for the user or one of their groups
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Neither the root nor the version is visible
+        """
+        user = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(self.grantee(user, grantee_kind), version, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    def test_grant_on_one_root_does_not_reach_another_roots_version(self) -> None:
+        """
+        GIVEN:
+            - Two private roots, each with a version
+            - The user may view only the first root
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - Only the first root and its version are visible
+        """
+        user = UserFactory()
+        first = DocumentFactory(owner=UserFactory())
+        first_version = DocumentFactory(root_document=first, owner=UserFactory())
+        second = DocumentFactory(owner=UserFactory())
+        second_version = DocumentFactory(root_document=second, owner=user)
+        grant_object(user, first, "view_document")
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[first.pk, first_version.pk],
+            expected_hidden=[second.pk, second_version.pk],
+        )
+
+    def test_user_in_several_groups(self) -> None:
+        """
+        GIVEN:
+            - A user in two groups
+            - Two private roots shared with one group each, and a third shared with nobody
+            - A version of each root
+        WHEN:
+            - The permitted document ids are resolved for the user
+        THEN:
+            - The two shared roots and their versions are visible
+            - The third root and its version are not
+        """
+        user = UserFactory()
+        groups = [Group.objects.create(name=f"group{i}") for i in range(2)]
+        user.groups.add(*groups)
+        shared = [DocumentFactory(owner=UserFactory()) for _ in groups]
+        for root, group in zip(shared, groups, strict=True):
+            grant_object(group, root, "view_document")
+        unshared = DocumentFactory(owner=UserFactory())
+        shared_versions = [
+            DocumentFactory(root_document=root, owner=UserFactory()) for root in shared
+        ]
+        unshared_version = DocumentFactory(root_document=unshared, owner=None)
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[
+                *(root.pk for root in shared),
+                *(version.pk for version in shared_versions),
+            ],
+            expected_hidden=[unshared.pk, unshared_version.pk],
+        )
+
+    def test_permission_is_resolved_through_the_root(self) -> None:
+        """
+        GIVEN:
+            - A private root document where the user may view and change
+        WHEN:
+            - The permitted ids are resolved for view, change and delete
+        THEN:
+            - The version is visible for view and change only
+        """
+        user = UserFactory()
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+        grant_object(user, root, "view_document", "change_document")
+
+        assert version.pk in set(permitted_document_ids(user))
+        assert version.pk in set(permitted_document_ids(user, perm="change_document"))
+        assert version.pk in set(
+            permitted_document_ids(user, perm="documents.change_document"),
+        )
+        assert version.pk not in set(
+            permitted_document_ids(user, perm="delete_document"),
+        )
+
+    def test_anonymous_sees_versions_of_unowned_roots_only(self) -> None:
+        """
+        GIVEN:
+            - A version owned by nobody under a private root
+            - A version owned by someone under an unowned root
+        WHEN:
+            - The permitted document ids are resolved for an anonymous user
+        THEN:
+            - Only the version of the unowned root is visible
+        """
+        private_root = DocumentFactory(owner=UserFactory())
+        private_version = DocumentFactory(root_document=private_root, owner=None)
+        open_root = DocumentFactory(owner=None)
+        open_version = DocumentFactory(root_document=open_root, owner=UserFactory())
+
+        assert_visible_document_ids(
+            permitted_document_ids(AnonymousUser()),
+            expected_visible=[open_root.pk, open_version.pk],
+            expected_hidden=[private_root.pk, private_version.pk],
+        )
+
+    def test_deleted_versions_follow_their_deleted_root(self) -> None:
+        """
+        GIVEN:
+            - A soft-deleted root document and its version, which deleting the
+              root soft-deletes too; the version is owned by someone else
+        WHEN:
+            - The permitted document ids are resolved with and without deleted
+              documents
+        THEN:
+            - Nothing is visible by default
+            - With deleted documents included, the version is visible to the
+              root's owner and not to the version's own owner
+        """
+        owner = UserFactory()
+        version_owner = UserFactory()
+        root = DocumentFactory(owner=owner)
+        version = DocumentFactory(root_document=root, owner=version_owner)
+        root.delete()
+
+        assert not {root.pk, version.pk} & set(permitted_document_ids(owner))
+        assert_visible_document_ids(
+            permitted_document_ids(owner, include_deleted=True),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+        assert_visible_document_ids(
+            permitted_document_ids(version_owner, include_deleted=True),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    @pytest.mark.parametrize(
+        "is_superuser",
+        [
+            pytest.param(False, id="regular-user"),
+            pytest.param(True, id="superuser"),
+        ],
+    )
+    def test_inactive_user_sees_no_versions(self, *, is_superuser: bool) -> None:
+        """
+        GIVEN:
+            - An inactive user, possibly a superuser, who owns a root and its version
+        WHEN:
+            - The permitted document ids are resolved for them
+        THEN:
+            - Nothing is visible
+        """
+        user = UserFactory(is_active=False, is_superuser=is_superuser)
+        root = DocumentFactory(owner=user)
+        version = DocumentFactory(root_document=root, owner=user)
+
+        assert_visible_document_ids(
+            permitted_document_ids(user),
+            expected_visible=[],
+            expected_hidden=[root.pk, version.pk],
+        )
+
+    def test_superuser_sees_all_versions(self) -> None:
+        """
+        GIVEN:
+            - A private root owned by someone else, with a version
+        WHEN:
+            - The permitted document ids are resolved for a superuser
+        THEN:
+            - Both the root and the version are visible
+        """
+        superuser = UserFactory(superuser=True)
+        root = DocumentFactory(owner=UserFactory())
+        version = DocumentFactory(root_document=root, owner=UserFactory())
+
+        assert_visible_document_ids(
+            permitted_document_ids(superuser),
+            expected_visible=[root.pk, version.pk],
+            expected_hidden=[],
+        )
+
+
+@pytest.mark.django_db
+class TestHasPermsOwnerAwareVersions:
+    """
+    The single-object check agrees with permitted_document_ids: a version is
+    authorized by its root document.
+    """
+
+    @pytest.mark.parametrize(
+        ("root_owner", "version_owner", "expected"),
+        [
+            pytest.param(
+                "other",
+                "nobody",
+                False,
+                id="unowned-version-of-private-root",
+            ),
+            pytest.param("other", "user", False, id="own-version-of-private-root"),
+            pytest.param("user", "other", True, id="foreign-version-of-own-root"),
+            pytest.param("nobody", "other", True, id="private-version-of-unowned-root"),
+        ],
+    )
+    def test_version_follows_root_owner(
+        self,
+        root_owner: str,
+        version_owner: str,
+        *,
+        expected: bool,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document and a version with differing owners
+        WHEN:
+            - The single-object check runs for the version
+        THEN:
+            - The version is allowed exactly when its root is
+        """
+        user = UserFactory()
+        owners = {"user": user, "other": UserFactory(), "nobody": None}
+        root = DocumentFactory(owner=owners[root_owner])
+        version = DocumentFactory(root_document=root, owner=owners[version_owner])
+
+        assert has_perms_owner_aware(user, "view_document", version) is expected
+        assert has_perms_owner_aware(user, "view_document", root) is expected
+
+    def test_grant_on_root_applies_and_grant_on_version_does_not(self) -> None:
+        """
+        GIVEN:
+            - A private root with a version, and a second private root with a version
+            - The user may change only the first root, and was granted the second
+              root's version directly
+        WHEN:
+            - The single-object check runs for each version
+        THEN:
+            - Only the first root's version is allowed
+        """
+        user = UserFactory()
+        shared_root = DocumentFactory(owner=UserFactory())
+        shared_version = DocumentFactory(root_document=shared_root, owner=UserFactory())
+        private_root = DocumentFactory(owner=UserFactory())
+        private_version = DocumentFactory(
+            root_document=private_root,
+            owner=UserFactory(),
+        )
+        grant_object(user, shared_root, "change_document")
+        grant_object(user, private_version, "change_document")
+
+        assert has_perms_owner_aware(user, "change_document", shared_version)
+        assert not has_perms_owner_aware(user, "change_document", private_version)
+
+    def test_other_models_use_their_own_owner(self) -> None:
+        """
+        GIVEN:
+            - A tag owned by someone else, and one owned by the user
+        WHEN:
+            - The single-object check runs for each
+        THEN:
+            - Only the user's own tag is allowed without a grant
+        """
+        user = UserFactory()
+        mine = TagFactory(owner=user)
+        theirs = TagFactory(owner=UserFactory())
+
+        assert has_perms_owner_aware(user, "view_tag", mine)
+        assert not has_perms_owner_aware(user, "view_tag", theirs)
+
+
 @pytest.mark.django_db
 class TestAiChatAllDocumentsPermissionBoundary:
     """

src/documents/views.py

@@ -174,7 +174,6 @@ from documents.permissions import TrashPermissions
 from documents.permissions import ViewDocumentsPermissions
 from documents.permissions import annotate_document_count_by_ids
 from documents.permissions import annotate_document_count_for_related_queryset
-from documents.permissions import documents_without_permitted_root
 from documents.permissions import get_document_count_filter_for_user
 from documents.permissions import get_objects_for_user_owner_aware
 from documents.permissions import has_global_statistics_permission
@@ -1560,7 +1559,7 @@ class DocumentViewSet(
         if request.user is not None and not has_perms_owner_aware(
             request.user,
             "change_document",
-            get_root_document(doc),
+            doc,
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -1623,7 +1622,7 @@ class DocumentViewSet(
         if request.user is not None and not has_perms_owner_aware(
             request.user,
             "change_document",
-            get_root_document(doc),
+            doc,
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -1876,7 +1875,7 @@ class DocumentViewSet(
             if currentUser is not None and not has_perms_owner_aware(
                 currentUser,
                 "view_document",
-                get_root_document(doc),
+                doc,
             ):
                 return HttpResponseForbidden("Insufficient permissions to view notes")
         except Document.DoesNotExist:
@@ -1898,7 +1897,7 @@ class DocumentViewSet(
                 if currentUser is not None and not has_perms_owner_aware(
                     currentUser,
                     "change_document",
-                    get_root_document(doc),
+                    doc,
                 ):
                     return HttpResponseForbidden(
                         "Insufficient permissions to create notes",
@@ -1941,7 +1940,7 @@ class DocumentViewSet(
             if currentUser is not None and not has_perms_owner_aware(
                 currentUser,
                 "change_document",
-                get_root_document(doc),
+                doc,
             ):
                 return HttpResponseForbidden("Insufficient permissions to delete notes")
 
@@ -1991,7 +1990,7 @@ class DocumentViewSet(
             if currentUser is not None and not has_perms_owner_aware(
                 currentUser,
                 "change_document",
-                get_root_document(doc),
+                doc,
             ):
                 return HttpResponseForbidden(
                     "Insufficient permissions to add share link",
@@ -2117,7 +2116,7 @@ class DocumentViewSet(
         documents = Document.objects.filter(pk__in=document_ids)
         if (
             request.user is not None
-            and documents_without_permitted_root(documents, request.user).exists()
+            and documents.exclude(id__in=permitted_document_ids(request.user)).exists()
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -2452,7 +2451,7 @@ class ChatStreamingView(GenericAPIView[Any]):
             if not has_perms_owner_aware(
                 request.user,
                 "view_document",
-                get_root_document(document),
+                document,
             ):
                 return HttpResponseForbidden("Insufficient permissions")
 
@@ -3009,12 +3008,8 @@ class DocumentOperationPermissionMixin(PassUserMixin, DocumentSelectionMixin):
             user.has_perm(
                 "documents.change_document",
             )
-            and not Document.global_objects.filter(
-                pk__in=[doc.pk for doc in root_docs],
-            )
-            .exclude(
-                pk__in=permitted_document_ids(user, perm="change_document"),
-            )
+            and not Document.global_objects.filter(pk__in=documents)
+            .exclude(pk__in=permitted_document_ids(user, perm="change_document"))
             .exists()
         )
 
@@ -3627,7 +3622,7 @@ class SelectionDataView(DocumentSelectionMixin, GenericAPIView[Any]):
         documents = Document.objects.filter(pk__in=ids)
         if (
             documents.count() != len(ids)
-            or documents_without_permitted_root(documents, request.user).exists()
+            or documents.exclude(id__in=permitted_document_ids(request.user)).exists()
         ):
             return HttpResponseForbidden("Insufficient permissions")
 
@@ -4124,21 +4119,16 @@ class BulkDownloadView(DocumentSelectionMixin, GenericAPIView[Any]):
             validated_data=serializer.validated_data,
         )
         documents = Document.objects.filter(pk__in=ids)
-        versioned_documents = []
         compression = serializer.validated_data.get("compression")
         content = serializer.validated_data.get("content")
         follow_filename_format = serializer.validated_data.get("follow_formatting")
 
-        permitted_ids = set(permitted_document_ids(request.user))
-        for document in documents:
-            root_doc = get_root_document(document)
-            if root_doc.pk not in permitted_ids:
-                return HttpResponseForbidden("Insufficient permissions")
-            versioned_documents.append(
-                get_latest_version_for_root(
-                    root_doc,
-                ),
-            )
+        if documents.exclude(id__in=permitted_document_ids(request.user)).exists():
+            return HttpResponseForbidden("Insufficient permissions")
+        versioned_documents = [
+            get_latest_version_for_root(get_root_document(document))
+            for document in documents
+        ]
 
         if content == "both":
             strategy_class = OriginalAndArchiveStrategy
@@ -4811,7 +4801,7 @@ class ShareLinkBundleViewSet(PassUserMixin, ModelViewSet[ShareLinkBundle]):
             )
 
         denied_id = (
-            documents_without_permitted_root(documents_qs, request.user)
+            documents_qs.exclude(id__in=permitted_document_ids(request.user))
             .order_by("pk")
             .values_list("pk", flat=True)
             .first()
@@ -5657,11 +5647,12 @@ class TrashView(ListModelMixin, PassUserMixin):
             if doc_ids is not None
             else self.filter_queryset(self.get_queryset()).all()
         )
-        if documents_without_permitted_root(
-            docs,
-            request.user,
-            perm="delete_document",
-            include_deleted=True,
+        if docs.exclude(
+            id__in=permitted_document_ids(
+                request.user,
+                perm="delete_document",
+                include_deleted=True,
+            ),
         ).exists():
             return HttpResponseForbidden("Insufficient permissions")
         action = serializer.validated_data.get("action")

src/paperless_ai/ai_classifier.py

@@ -4,8 +4,7 @@ from django.conf import settings
 from django.contrib.auth.models import User
 
 from documents.models import Document
-from documents.permissions import permitted_object_ids
-from documents.permissions import restrict_queryset_to_visible
+from documents.permissions import permitted_document_ids
 from documents.permissions import user_is_unrestricted
 from paperless.config import AIConfig
 from paperless_ai.base_model import ClassificationSuggestions
@@ -54,8 +53,8 @@ def _fulltext_similar_documents(
     active superuser - see user_is_unrestricted) is normalized to ``None``
     before calling, since the backend's permission filter has no superuser
     short-circuit of its own. Results are re-checked with
-    restrict_queryset_to_visible() since Tantivy's indexed permission fields
-    lag the DB via async reindexing.
+    permitted_document_ids() since Tantivy's indexed permission fields lag the
+    DB via async reindexing and judge a version by its own owner.
     """
     from documents.search import get_backend
 
@@ -69,10 +68,9 @@ def _fulltext_similar_documents(
     )
     if not unrestricted:
         allowed_ids = set(
-            restrict_queryset_to_visible(
-                Document.objects.filter(pk__in=similar_ids),
-                user,
-                "view_document",
+            Document.objects.filter(
+                pk__in=similar_ids,
+                id__in=permitted_document_ids(user),
             ).values_list("pk", flat=True),
         )
         similar_ids = [doc_id for doc_id in similar_ids if doc_id in allowed_ids]
@@ -200,13 +198,13 @@ def get_taxonomy_context(
             # quadratic scan in the vector store at best, and past ~32,763
             # documents a hard sqlite3.OperationalError (SQLite's
             # bound-parameter limit) at worst.
-            # permitted_object_ids() has its own superuser shortcut that would
+            # permitted_document_ids() has its own superuser shortcut that would
             # return every Document's id anyway, so this changes nothing about
             # which documents are considered -- only how we get there.
             visible_document_ids = (
                 None
                 if user_is_unrestricted(user)
-                else list(permitted_object_ids(user, Document, "view_document"))
+                else list(permitted_document_ids(user))
             )
             nodes = retrieve_similar_nodes(
                 document,

src/paperless_ai/tests/test_ai_classifier.py

@@ -552,7 +552,7 @@ class TestGetTaxonomyContextVisibility:
             return_value=[],
         )
         mock_permitted = mocker.patch(
-            "paperless_ai.ai_classifier.permitted_object_ids",
+            "paperless_ai.ai_classifier.permitted_document_ids",
         )
         user = UserFactory.create(is_superuser=True)
 
@@ -582,7 +582,7 @@ class TestGetTaxonomyContextVisibility:
             return_value=[],
         )
         mock_permitted = mocker.patch(
-            "paperless_ai.ai_classifier.permitted_object_ids",
+            "paperless_ai.ai_classifier.permitted_document_ids",
         )
 
         get_taxonomy_context(document, None)
@@ -611,16 +611,55 @@ class TestGetTaxonomyContextVisibility:
             return_value=[],
         )
         mock_permitted = mocker.patch(
-            "paperless_ai.ai_classifier.permitted_object_ids",
+            "paperless_ai.ai_classifier.permitted_document_ids",
             return_value=[1, 2, 3],
         )
         user = UserFactory.create(is_superuser=False)
 
         get_taxonomy_context(document, user)
 
-        mock_permitted.assert_called_once_with(user, Document, "view_document")
+        mock_permitted.assert_called_once_with(user)
         assert mock_retrieve.call_args.kwargs["document_ids"] == [1, 2, 3]
 
+    @pytest.mark.django_db
+    @override_settings(LLM_EMBEDDING_BACKEND="huggingface")
+    def test_version_of_private_root_is_not_visible(
+        self,
+        mocker: pytest_mock.MockerFixture,
+    ) -> None:
+        """
+        GIVEN:
+            - A private root document owned by someone else
+            - A version of it whose own owner is unset, as when the root
+              changed hands after the version was created
+        WHEN:
+            - get_taxonomy_context() is called for a non-superuser
+        THEN:
+            - Neither the root nor the version is in the visible ids passed to
+              retrieve_similar_nodes(), since a version follows its root
+        """
+        owner = UserFactory.create()
+        viewer = UserFactory.create(is_superuser=False)
+        root = DocumentFactory.create(content="private", owner=owner)
+        version = DocumentFactory.create(
+            content="private",
+            owner=None,
+            root_document=root,
+            version_index=1,
+        )
+        source = DocumentFactory.create(content="Some content", owner=viewer)
+        mock_retrieve = mocker.patch(
+            "paperless_ai.ai_classifier.retrieve_similar_nodes",
+            return_value=[],
+        )
+
+        get_taxonomy_context(source, viewer)
+
+        visible = mock_retrieve.call_args.kwargs["document_ids"]
+        assert source.pk in visible
+        assert root.pk not in visible
+        assert version.pk not in visible
+
 
 @pytest.mark.django_db
 class TestFulltextSimilarDocuments:
@@ -803,7 +842,7 @@ class TestFulltextSimilarDocuments:
             - _fulltext_similar_documents() is called with that user
         THEN:
             - Only the still-permitted document is returned - the DB
-              re-check via restrict_queryset_to_visible() must catch the
+              re-check via permitted_document_ids() must catch the
               document Tantivy's stale index still thinks is visible
         """
         owner = UserFactory.create()
@@ -834,6 +873,45 @@ class TestFulltextSimilarDocuments:
 
         assert [s["document_id"] for s in result] == [permitted.pk]
 
+    def test_excludes_version_of_private_root_for_regular_user(
+        self,
+        fulltext_backend: TantivyBackend,
+    ) -> None:
+        """
+        GIVEN:
+            - A regular user and a private root owned by someone else
+            - A version of that root with no owner of its own, which the
+              Tantivy index therefore treats as visible to everyone
+        WHEN:
+            - _fulltext_similar_documents() is called with that user
+        THEN:
+            - The version is not returned, since the DB re-check judges it by
+              its root
+        """
+        owner = UserFactory.create()
+        viewer = UserFactory.create(is_superuser=False)
+        source = DocumentFactory.create(
+            content="shared content phrase",
+            owner=viewer,
+        )
+        root = DocumentFactory.create(
+            content="shared content phrase",
+            owner=owner,
+        )
+        version = DocumentFactory.create(
+            content="shared content phrase",
+            owner=None,
+            root_document=root,
+            version_index=1,
+        )
+        fulltext_backend.add_or_update(source)
+        fulltext_backend.add_or_update(root)
+        fulltext_backend.add_or_update(version)
+
+        result = _fulltext_similar_documents(source, user=viewer, top_k=5)
+
+        assert version.pk not in [s["document_id"] for s in result]
+
 
 @pytest.mark.django_db
 @override_settings(LLM_EMBEDDING_BACKEND="huggingface")