CVE-2026-77639

Name	CVE-2026-77639
Description	Tor before 0.4.9.9 was prone to a compression bomb bypass where an attacker could concatenate many gzip or zlib sub-streams, each just under the per-stream detection threshold, to avoid the compression bomb check entirely. This is TROVE-2026-022.
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, bullseye (security)	0.4.5.16-1	vulnerable
	bookworm, bookworm (security)	0.4.9.11-0+deb12u1	fixed
	trixie, trixie (security)	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/41275