Bug 2455935 (CVE-2026-3902)

Summary:	CVE-2026-3902 Django: Django: Header spoofing via ambiguous header mapping
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	anthomas, brasmith, caswilli, cmyers, cochase, dnakabaa, dranck, dschmidt, ehelms, erezende, ggainey, jlanda, jmitchel, juwatts, jwong, kaycoth, kshier, lcouzens, mhulan, nmoumoul, omaciel, osousa, pcreech, rchan, simaishi, smallamp, smcdonal, stcannon, teagle, tmalecek, ttakamiy, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Django. A remote attacker can exploit an ambiguous mapping of header variants (with hyphens or underscores) to a single version with underscores in `ASGIRequest`. This vulnerability allows the attacker to spoof headers, potentially leading to unauthorized actions or misdirection within the application.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-04-07 15:03:10 UTC

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.