CVE-2026-55655

Name	CVE-2026-55655
Description	A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session.
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
openssh (PTS)	bookworm	1:9.2p1-2+deb12u10	fixed
	bookworm (security)	1:9.2p1-2+deb12u9	fixed
	trixie	1:10.0p1-7+deb13u4	fixed
	trixie (security)	1:10.0p1-7+deb13u2	fixed
	forky	1:10.4p1-5	fixed
	sid	1:10.5p1-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
openssh	source	(unstable)	(not affected)

- openssh <not-affected> (Red Hat-specific patch, see bug #1143936)
https://bugzilla.redhat.com/show_bug.cgi?id=2462250