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

Vulnerability summary

CVE-2026-87975 is a medium (CVSS 5.3) vulnerability in djangoproject django. EPSS estimates a 0.23% chance of exploitation in the next 30 days, higher than 13.6% of scored vulnerabilities.

Timeline

1. 06-10-2026
   PublishedVulnerability first disclosed.
2. 06-10-2026
   Last modifiedVulnerability information updated.

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.

• CWE-639Authorization Bypass Through User-Controlled KeyThe system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.