Instituto Nacional de ciberseguridad. Sección Incibe
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CVE-2026-55655

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
23/06/2026
Last modified:
30/07/2026

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.

Impact

Vector 3.x
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 5.00 MEDIUM
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N

Attack Vector (AV): Local
Attack Complexity (AC): High
Privileges Required (PR): Low
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): Low
Availability (A): None

Base Score 3.x
5.00
Severity 3.x
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:openbsd:openssh:-:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools