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.
Published: 2026-06-23
Score: 5 Medium
EPSS: < 1% Very Low
KEV: No
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

Vendor Workaround

To mitigate this issue, disable X11 forwarding on OpenSSH clients when it is not required. This can be achieved by avoiding the use of `-X` or `-Y` options when invoking `ssh`, or by setting `ForwardX11 no` in the SSH client configuration file (`~/.ssh/config` or `/etc/ssh/ssh_config`). Disabling X11 forwarding will prevent the client from attempting to establish X11 connections, thereby removing the attack vector.

Tracking

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Advisories

No advisories yet.

References
Link Providers
https://access.redhat.com/errata/RHSA-2026:36759 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:47755 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:47756 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:47757 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:54387 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:58981 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:76748 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:76993 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:80513 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82749 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82750 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82751 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82752 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82753 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82754 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82755 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82756 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82757 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82758 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82759 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82761 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82762 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82763 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82897 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82898 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82899 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82900 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82901 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82902 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82903 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82904 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82907 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82908 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82909 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82910 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82912 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82913 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82914 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82915 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82916 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82917 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82918 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82920 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82921 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82922 cve-icon cve-icon
https://access.redhat.com/errata/RHSA-2026:82923 cve-icon cve-icon
https://access.redhat.com/security/cve/CVE-2026-55655 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2462250 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-55655 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-55655 cve-icon
History

Wed, 14 Oct 2026 19:30:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:openshift_ai:3.0::el9
cpe:/a:redhat:openshift_ai:3.2::el9
cpe:/a:redhat:openshift_ai:3.3::el9
cpe:/a:redhat:openshift_ai:3.5::el9
References

Wed, 14 Oct 2026 07:00:00 +0000

Type Values Removed Values Added
First Time appeared Redhat openshift Ai
CPEs cpe:/a:redhat:openshift_ai:3.4::el9
Vendors & Products Redhat openshift Ai
References

Mon, 12 Oct 2026 08:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.6::appstream
cpe:/o:redhat:rhel_eus:9.6::baseos
Vendors & Products Redhat rhel Eus
References

Wed, 07 Oct 2026 02:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel E4s
CPEs cpe:/a:redhat:rhel_e4s:9.4::appstream
cpe:/o:redhat:rhel_e4s:9.4::baseos
Vendors & Products Redhat rhel E4s
References

Tue, 06 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux Eus
CPEs cpe:/o:redhat:enterprise_linux_eus:10.0
Vendors & Products Redhat enterprise Linux Eus
References

Tue, 25 Aug 2026 10:00:00 +0000

Type Values Removed Values Added
References

Wed, 12 Aug 2026 16:00:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhui
CPEs cpe:/a:redhat:rhui:5::el9
Vendors & Products Redhat rhui
References

Thu, 30 Jul 2026 09:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:9
cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/o:redhat:enterprise_linux:10.2
cpe:/o:redhat:enterprise_linux:9::baseos
References

Thu, 30 Jul 2026 06:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:8 cpe:/a:redhat:enterprise_linux:8::appstream
cpe:/o:redhat:enterprise_linux:8::baseos
References

Wed, 08 Jul 2026 14:15:00 +0000

Type Values Removed Values Added
References

Wed, 24 Jun 2026 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Openssh
Openssh openssh
Redhat hardened Images
Redhat openshift Container Platform
Vendors & Products Openssh
Openssh openssh
Redhat hardened Images
Redhat openshift Container Platform

Tue, 23 Jun 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 23 Jun 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 23 Jun 2026 03:45:00 +0000

Type Values Removed Values Added
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.
Title Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions
First Time appeared Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
Weaknesses CWE-923
CPEs cpe:/a:redhat:hummingbird:1
cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat hummingbird
Redhat openshift
References
Metrics cvssV3_1

{'score': 5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N'}


Subscriptions

Openbsd Openssh
Openssh Openssh
Redhat Enterprise Linux Enterprise Linux Eus Hardened Images Hummingbird Openshift Openshift Ai Openshift Container Platform Rhel E4s Rhel Eus Rhui
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-10-14T19:11:14.188Z

Reserved: 2026-06-16T23:55:05.737Z

Link: CVE-2026-55655

cve-icon Vulnrichment

Updated: 2026-06-23T12:21:44.889Z

cve-icon NVD

Status : Modified

Published: 2026-06-23T04:17:40.787

Modified: 2026-10-14T20:17:49.637

Link: CVE-2026-55655

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-06-22T23:22:11Z

Links: CVE-2026-55655 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-24T16:06:36Z

Weaknesses