CVE-2026-3902: Django vulnerable to ASGI header spoofing via underscore/hyphen conflation

April 7, 2026 (updated April 8, 2026)

An issue was discovered in 6.0 before 6.0.4, 5.2 before 5.2.13, and 4.2 before 4.2.30. ASGIRequest allows a remote attacker to spoof headers by exploiting an ambiguous mapping of two header variants (with hyphens or with underscores) to a single version with underscores.

Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Tarek Nakkouch for reporting this issue.

References

docs.djangoproject.com/en/dev/releases/security
github.com/advisories/GHSA-mvfq-ggxm-9mc5
github.com/django/django
groups.google.com/g/django-announce
nvd.nist.gov/vuln/detail/CVE-2026-3902
www.djangoproject.com/weblog/2026/apr/07/security-releases

Code Behaviors & Features

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