CVE-2026-84429: Djangoproject Django

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

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.utils.http.parse_header_parameters()` was subject to a potential denial-of-service attack due to quadratic time complexity when parsing a value with many separators inside a quoted parameter. An unauthenticated request could reach this parsing through headers such as `Accept` or `Content-Type`, for instance via the content negotiation performed by `HttpRequest.accepts()`. The per-call length limit does not bound the combined size of repeated headers. 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 Jisung Chae for reporting this issue.

Affected products

• Djangoproject Django: from 6.1, before 6.1.2 (fixed in 6.1.2); from 6.0, before 6.0.9 (fixed in 6.0.9); from 5.2, before 5.2.18 (fixed in 5.2.18)

Published 2026-10-06. Last modified 2026-10-06.