CVE-2026-87975Privilege abuse in model formsets with editable primary keys

Official description

An issue was discovered in Django 6.1 before 6.1.2, 6.0 before 6.0.9, and 5.2 before 5.2.18. `django.forms.models.BaseModelFormSet.save_existing_objects()` used the presence of a primary key on a submitted form's instance as evidence that the instance belonged to the formset's limiting queryset. An object outside that queryset is represented by a newly constructed instance whose primary key can still be populated from submitted data when the model's primary key is a field accepted by the form, such as a `OneToOneField` or parent link used as the primary key of an inline formset's model, or a natural or UUID primary key included in the form's fields. This allows an authenticated user permitted to submit such a formset to delete rows outside the limiting queryset, without any permission on the targeted object, via forged management-form data marking an out-of-queryset object for deletion. Models using the default AutoField primary key are not affected. Earlier, unsupported Django series (such as 5.1.x, 5.0.x, and 4.2.x) were not evaluated and may also be affected. Django would like to thank Seonggwon Yoon for reporting this issue.

Affected packages & fixed versions

Affected products (as reported)

References

• Django security archive vendor-advisory
• Django releases announcements mailing-list
• https://github.com/django/django/commit/83cbd21be57483e6b3eb6e4688a561c841aff75e patch
• https://github.com/django/django/commit/cce6c57ed30ea83725f9d6abb2fe5ee932bab107 patch
• https://github.com/django/django/commit/b83ab92bc5474558b083a840ea4628b3261b2cfe patch
• https://github.com/django/django/commit/ff27883ca055aa9ab23015b50674a5b10dfe5a41 patch
• Django security releases issued: 6.1.2, 6.0.9, and 5.2.18 vendor-advisory