What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-07 · updated 2026-10-26
• Weakness: CWE-290

Description

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.

Affected products

• Django: from 4.2 before 4.2.30; from 5.2 before 5.2.13; from 6.0 before 6.0.4 — fixed in 4.2.30, 5.2.13, 6.0.4

How to fix

Upgrade to a fixed version: Django 4.2.30, 5.2.13, 6.0.4. Check the vendor advisory for mitigations.

References

• https://docs.djangoproject.com/en/dev/releases/security/
• https://groups.google.com/g/django-announce
• https://www.djangoproject.com/weblog/2026/apr/07/security-releases/

Get alerted when CVE-2026-3902 or the next vulnerability affects your stack