Django FormSet PK Bypass: Delete External Rows (<=6.1.2, <=6.0.9, <=5.2.18)
CVE-2026-87975 Published on October 6, 2026
Privilege abuse in model formsets with editable primary keys
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.
Timeline
Initial report received.
Vulnerability confirmed. 14 days later.
Security release issued. 20 days later.
Weakness Type
What is an Insecure Direct Object Reference / IDOR Vulnerability?
The 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.
CVE-2026-87975 has been classified to as an Insecure Direct Object Reference / IDOR vulnerability or weakness.
Products Associated with CVE-2026-87975
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Affected Versions
djangoproject Django:- Version 6.1 and below 6.1.2 is affected.
- Version 6.1.2 is unaffected.
- Version 6.0 and below 6.0.9 is affected.
- Version 6.0.9 is unaffected.
- Version 5.2 and below 5.2.18 is affected.
- Version 5.2.18 is unaffected.