CVE-2026-55655

Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions

MEDIUM
6.1
CVSS Score
Published: June 23, 2026 at 03:36 AM UTC
Updated: October 29, 2026 at 11:16 PM UTC
3 products affected across 2 vendorsEnterprise LinuxOpenSSHOpenShift Container Platform

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Severity
MEDIUM6.1
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

All versions
Vendor states this is fixed in 0:8.0p1-30.el8_10 (unaffected)
Vendor states this is fixed in 0:8.7p1-38.el9_4.10 (unaffected)
Vendor states this is fixed in 0:8.7p1-45.el9_6.5 (unaffected)
Vendor states this is fixed in 0:9.9p1-25.el10_2 (unaffected)
Vendor states this is fixed in 0:9.9p1-7.el10_0.5 (unaffected)
Vendor states this is fixed in 0:9.9p1-9.el9_8 (unaffected)
All versions
Vendor states this is fixed in 4 (unknown)

References (50)

VDB Entryx_refsource_REDHATVendor Advisory
Source: cverecord
https://access.redhat.com/security/cve/CVE-2026-55655
Issue Trackingx_refsource_REDHATVendor Advisory
Source: cverecord
https://bugzilla.redhat.com/show_bug.cgi?id=2462250
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:36759
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:47755
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:47756
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:47757
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:54387
Vendor Advisoryx_refsource_REDHAT
Source: cverecord
https://access.redhat.com/errata/RHSA-2026:58981

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-923

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