CVE-2026-55655
A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections.
Does this matter?
Lower severity and a low EPSS score (0.09%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.1 MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
- EPSS
- 0.09% probability · 0th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-923
- Affected
- openbsd/openssh · redhat/enterprise linux
- Source
- secalert@redhat.com
References
- https://access.redhat.com/errata/RHSA-2026:36759
- https://access.redhat.com/errata/RHSA-2026:47755
- https://access.redhat.com/errata/RHSA-2026:47756
- https://access.redhat.com/errata/RHSA-2026:47757
- https://access.redhat.com/errata/RHSA-2026:54387
- https://access.redhat.com/errata/RHSA-2026:58981
- https://access.redhat.com/security/cve/CVE-2026-55655Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2462250Issue Tracking, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.