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Vulnerability record · CVE-2026-55655 · published 23 June 2026

CVE-2026-55655: Openbsd openssh vulnerability

Openbsd · Openssh

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.

6.1 CVSS 3.1 Medium EPSS 0.12% · top 98.2% CWE-923 · CWE-923
6.1CVSS 3.1 base score
0.12%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
8References
1 Sep 2026Last modified by NVD

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/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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-2026-55655 Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2462250 Issue TrackingVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-55655), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.