DescriptionGunicorn fails to properly validate Transfer-Encoding headers, leading to HTTP Request Smuggling (HRS) vulnerabilities. By crafting requests with conflicting Transfer-Encoding headers, attackers can bypass security restrictions and access restricted endpoints. This issue is due to Gunicorn's handling of Transfer-Encoding headers, where it incorrectly processes requests with multiple, conflicting Transfer-Encoding headers, treating them as chunked regardless of the final encoding specified. This vulnerability allows for a range of attacks including cache poisoning, session manipulation, and data exposure.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1069126

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
gunicorn (PTS)buster19.9.0-1vulnerable
sid, trixie, bookworm20.1.0-6vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs


[bookworm] - gunicorn <no-dsa> (Minor issue)
[bullseye] - gunicorn <no-dsa> (Minor issue)
[buster] - gunicorn <postponed> (Minor issue)

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