CVE-2026-40561

Name	CVE-2026-40561
Description	Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starlet incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence. An attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy.
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)
Debian Bugs	1135584

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
starlet (PTS)	bullseye	0.31-1.1	vulnerable
	forky, sid, bookworm, trixie	0.31-2	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
starlet	source	(unstable)	(unfixed)			1135584

Notes

https://lists.security.metacpan.org/cve-announce/msg/39593408/
Fixed by: https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0