[4.2.x] Refs CVE-2026-1312 -- Raised ValueError when FilteredRelation aliases contain periods.

This prevents failures at the database layer, given that aliases in the
ON clause are not quoted.

Systematically quoting aliases even in FilteredRelation is tracked in
https://code.djangoproject.com/ticket/36795.

Backport of 005d60d97c4dfb117503bdb6f2facfcaf9315d84 from main.

1 files changed, 13 insertions, 0 deletions

diff --git a/tests/filtered_relation/tests.py b/tests/filtered_relation/tests.py
index 0fce8b092a..4847d1f04b 100644
--- a/tests/filtered_relation/tests.py
+++ b/tests/filtered_relation/tests.py
@@ -211,6 +211,19 @@ class FilteredRelationTests(TestCase):
             str(queryset.query),
         )
 
+    def test_period_forbidden(self):
+        msg = (
+            "FilteredRelation doesn't support aliases with periods (got 'book.alice')."
+        )
+        with self.assertRaisesMessage(ValueError, msg):
+            Author.objects.annotate(
+                **{
+                    "book.alice": FilteredRelation(
+                        "book", condition=Q(book__title__iexact="poem by alice")
+                    )
+                }
+            )
+
     def test_multiple(self):
         qs = (
             Author.objects.annotate(