CVE-2026-77641

Name	CVE-2026-77641
Description	tor before 0.4.9.9 was prone to a NULL write after free when sending a CONFLUX_SWITCH cell fails. The return value of relay_send_command_from_edge() was ignored, so a send failure (which calls circuit_mark_for_close() and removes the leg via cfx_del_leg()) would go undetected, causing the caller to write to the now-freed current leg and resulting in a crash. This is TROVE-2026-017.
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)
References	DSA-6372-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
tor (PTS)	bullseye (security), bullseye	0.4.5.16-1	vulnerable
	bookworm, bookworm (security)	0.4.9.11-0+deb12u1	fixed
	trixie (security), trixie	0.4.9.11-0+deb13u1	fixed
	forky, sid	0.4.9.11-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin
tor	source	bullseye	(unfixed)	end-of-life
tor	source	trixie	0.4.9.11-0+deb13u1		DSA-6372-1
tor	source	(unstable)	0.4.9.9-1

[bullseye] - tor <end-of-life> (see DSA 5562)
https://gitlab.torproject.org/tpo/core/tor/-/work_items/41263