CVE-2026-63381

Name	CVE-2026-63381
Description	Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. 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-c2pj-cg4r-88c8
Fixed by: https://github.com/libevent/libevent/commit/5cb95ba2f804f8aff46f88d58391c71e1251cd1c (release-2.1.13-stable)
Fixed by: https://github.com/libevent/libevent/commit/9db091b04f569be3a700fa9860ef02f90b830af9 (release-2.2.2-alpha)