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[4.2.x] Fixed CVE-2026-4277 — Checked add permissions in GenericInli… · django/django@051f390 · GitHub
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[4.2.x] Fixed CVE-2026-4277 — Checked add permissions in GenericInlineModelAdmin.
Edit permissions were still checked as part of ordinary form validation, but because GenericInlineModelAdmin overrides get_formset(), it lacked InlineModelAdmin’s dynamic DeleteProtectedModelForm.has_changed() logic for checking permissions server-side, leaving the add case unaddressed. This change reimplements the relevant part of InlineModelAdmin.get_formset(). Thanks N05ec@LZU-DSLab for the report, and Natalia Bidart, Markus Holtermann, and Simon Charette for reviews. Backport of ef8b25d from main.
1 parent 4412731 commit 051f390

3 files changed

Lines changed: 132 additions & 9 deletions

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‎django/contrib/contenttypes/admin.py‎

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@@ -127,6 +127,21 @@ def get_formset(self, request, obj=None, **kwargs):
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**kwargs,
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}
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base_model_form = defaults["form"]
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can_change = self.has_change_permission(request, obj) if request else True
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can_add = self.has_add_permission(request, obj) if request else True
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class PermissionProtectedModelForm(base_model_form):
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def has_changed(self):
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# Protect against unauthorized edits.
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if not can_change and not self.instance._state.adding:
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return False
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if not can_add and self.instance._state.adding:
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return False
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return super().has_changed()
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defaults["form"] = PermissionProtectedModelForm
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if defaults["fields"] is None and not modelform_defines_fields(
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defaults["form"]
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):

‎docs/releases/4.2.30.txt‎

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@@ -26,3 +26,13 @@ behavior of :pypi:`Daphne <daphne>`, the reference server for ASGI.
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This issue has severity "low" according to the :ref:`Django security policy
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<security-disclosure>`.
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CVE-2026-4277: Privilege abuse in ``GenericInlineModelAdmin``
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=============================================================
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Add permissions on inline model instances were not validated on submission of
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forged ``POST`` data in
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:class:`~django.contrib.contenttypes.admin.GenericInlineModelAdmin`.
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This issue has severity "low" according to the :ref:`Django security policy
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<security-disclosure>`.

‎tests/generic_inline_admin/tests.py‎

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Original file line numberDiff line numberDiff line change
@@ -1,16 +1,16 @@
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from django.contrib import admin
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from django.contrib.admin.sites import AdminSite
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from django.contrib.auth.models import User
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from django.contrib.auth.models import Permission, User
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from django.contrib.contenttypes.admin import GenericTabularInline
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from django.contrib.contenttypes.models import ContentType
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from django.forms.formsets import DEFAULT_MAX_NUM
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from django.forms.models import ModelForm
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from django.test import RequestFactory, SimpleTestCase, TestCase, override_settings
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from django.urls import reverse
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from .admin import MediaInline, MediaPermanentInline
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from .admin import MediaInline, MediaPermanentInline, PhoneNumberInline
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from .admin import site as admin_site
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from .models import Category, Episode, EpisodePermanent, Media, PhoneNumber
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from .models import Category, Contact, Episode, EpisodePermanent, Media, PhoneNumber
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class TestDataMixin:
@@ -295,12 +295,102 @@ def test_delete(self):
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@override_settings(ROOT_URLCONF="generic_inline_admin.urls")
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class NoInlineDeletionTest(SimpleTestCase):
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def test_no_deletion(self):
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inline = MediaPermanentInline(EpisodePermanent, admin_site)
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fake_request = object()
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formset = inline.get_formset(fake_request)
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self.assertFalse(formset.can_delete)
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class GenericInlineAdminPermissionsTest(TestCase):
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factory = RequestFactory()
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@classmethod
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def setUpTestData(cls):
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cls.user = User(username="admin", is_staff=True, is_active=True)
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cls.user.set_password("secret")
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cls.user.save()
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# User always has all permissions on Contact (parent) model.
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# Permissions on the inlines vary per test.
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cls.contact_type = ContentType.objects.get_for_model(Contact)
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cls.user.user_permissions.add(
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*Permission.objects.filter(content_type=cls.contact_type)
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)
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def test_add_inline_without_add_permission(self):
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self.client.force_login(self.user)
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inline_view_perm = Permission.objects.get(codename="view_phonenumber")
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self.user.user_permissions.add(inline_view_perm)
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category_id = Category.objects.create(name="test").pk
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prefix = "generic_inline_admin-phonenumber-content_type-object_id"
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post_data = {
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"name": "Barbara",
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# inline data
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f"{prefix}-TOTAL_FORMS": "1",
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f"{prefix}-INITIAL_FORMS": "0",
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f"{prefix}-MIN_NUM_FORMS": "0",
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f"{prefix}-MAX_NUM_FORMS": "0",
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f"{prefix}-0-id": "",
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f"{prefix}-0-phone_number": "555-555-5555",
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f"{prefix}-0-category": str(category_id),
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}
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request = self.factory.get(reverse("admin:generic_inline_admin_contact_add"))
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request.user = self.user
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inline = PhoneNumberInline(Contact, AdminSite())
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FormSet = inline.get_formset(request)
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formset = FormSet(
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data=post_data, prefix=prefix, instance=Contact(name="Barbara")
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)
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self.assertIs(formset.is_valid(), True)
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self.assertIs(formset.has_changed(), False)
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self.assertEqual(formset.save(commit=False), [])
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def test_add_inline_with_change_permission_only(self):
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"""
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Forged new inline instances are ignored without add permissions, but
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but edits still work with edit permissions.
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"""
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self.client.force_login(self.user)
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inline_perms = Permission.objects.filter(
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codename__in=("view_phonenumber", "change_phonenumber")
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)
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self.user.user_permissions.add(*inline_perms)
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category_id = Category.objects.create(name="test").pk
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contact = Contact.objects.create(name="Barbara")
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existing_number = PhoneNumber.objects.create(
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category_id=category_id,
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content_type=self.contact_type,
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object_id=contact.pk,
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phone_number="555-555-5555",
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)
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prefix = "generic_inline_admin-phonenumber-content_type-object_id"
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post_data = {
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"id": str(contact.pk),
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"name": "Barbara",
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# inline data
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f"{prefix}-TOTAL_FORMS": "2",
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f"{prefix}-INITIAL_FORMS": "1",
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f"{prefix}-MIN_NUM_FORMS": "0",
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f"{prefix}-MAX_NUM_FORMS": "0",
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# Attempt to edit the existing phone number value.
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f"{prefix}-0-id": str(existing_number.id),
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f"{prefix}-0-phone_number": "111-111-1111",
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f"{prefix}-0-category": str(category_id),
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# Attempt to forge a new phone number.
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f"{prefix}-1-id": "",
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f"{prefix}-1-phone_number": "666-666-6666",
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f"{prefix}-1-category": str(category_id),
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"_save": "Save",
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}
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request = self.factory.get(
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reverse("admin:generic_inline_admin_contact_change", args=[contact.pk])
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)
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request.user = self.user
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inline = PhoneNumberInline(Contact, AdminSite())
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FormSet = inline.get_formset(request)
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formset = FormSet(data=post_data, prefix=prefix, instance=contact)
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self.assertIs(formset.is_valid(), True)
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self.assertIs(formset.has_changed(), True)
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# The edit succeeds; the add is ignored.
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self.assertEqual(formset.save(commit=False), [existing_number])
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class MockRequest:
@@ -316,6 +406,14 @@ def has_perm(self, perm, obj=None):
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request.user = MockSuperUser()
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@override_settings(ROOT_URLCONF="generic_inline_admin.urls")
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class NoInlineDeletionTest(SimpleTestCase):
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def test_no_deletion(self):
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inline = MediaPermanentInline(EpisodePermanent, admin_site)
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formset = inline.get_formset(request)
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self.assertFalse(formset.can_delete)
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@override_settings(ROOT_URLCONF="generic_inline_admin.urls")
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class GenericInlineModelAdminTest(SimpleTestCase):
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def setUp(self):

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