CVE-2026-26962

Name	CVE-2026-26962
Description	Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
ruby-rack (PTS)	bullseye	2.1.4-3+deb11u2	vulnerable
	bullseye (security)	2.1.4-3+deb11u5	vulnerable
	bookworm	2.2.20-0+deb12u1	vulnerable
	bookworm (security)	2.2.22-0+deb12u1	vulnerable
	trixie	3.1.18-1~deb13u1	vulnerable
	trixie (security)	3.1.20-0+deb13u1	vulnerable
	forky	3.1.18-1	vulnerable
	sid	3.2.5-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
ruby-rack	source	experimental	3.2.6-1
ruby-rack	source	(unstable)	(unfixed)

Notes

https://github.com/rack/rack/security/advisories/GHSA-rx22-g9mx-qrhv
Fixed by: https://github.com/rack/rack/commit/d50c4d3dab62fa80b2a276271d0d4fb338cfa7df (v3.2.6)