CVE-2026-34830

Name	CVE-2026-34830
Description	Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Sendfile#map_accel_path interpolates the value of the X-Accel-Mapping request header directly into a regular expression when rewriting file paths for X-Accel-Redirect. Because the header value is not escaped, an attacker who can supply X-Accel-Mapping to the backend can inject regex metacharacters and control the generated X-Accel-Redirect response header. In deployments using Rack::Sendfile with x-accel-redirect, this can allow an attacker to cause nginx to serve unintended files from configured internal locations. This issue has been patched in versions 2.2.23, 3.1.21, and 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-qv7j-4883-hwh7
Fixed by: https://github.com/rack/rack/commit/a57bc140247f904dc1e3302badedcb73645072c7 (v3.2.6)
Fixed by: https://github.com/rack/rack/commit/59a0966a484f2903833fa3e4c81919d3c645738d (v3.1.21)
Fixed by: https://github.com/rack/rack/commit/7f288de93768b5cc44a5f4ed1ac02470d8fe52f4 (v2.2.23)