CVE-2026-63379

Name	CVE-2026-63379
Description	Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
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
libevent (PTS)	bullseye	2.1.12-stable-1	vulnerable
	bookworm	2.1.12-stable-8	vulnerable
	trixie	2.1.12-stable-10	vulnerable
	forky, sid	2.1.13-stable-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libevent	source	(unstable)	2.1.13-stable-1

Notes

https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6
Fixed by: https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636 (release-2.1.13-stable)
Fixed by: https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485 (release-2.2.2-alpha)