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.
CVE-2026-55655
CVSS base score
5.0 (v3.1)
Severity
MEDIUM
Attack vector
Local
Weakness
CWE-923
Last modified
October 30, 2026
CVSS vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
Affected products
openbsd openssh
redhat enterprise linux