CVE-2026-55655

MEDIUM

5.0

CVSS v3

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.

CWE-923

How to fix

Remediation Available

opensshRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:main@srcRHSA-2026:36759

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:main@aarch64RHSA-2026:36759

Fixed in:main@x86_64RHSA-2026:36759

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

opensshRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:main@x86_64RHSA-2026:36759

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:main@aarch64RHSA-2026:36759

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:main@srcRHSA-2026:36759

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-askpassRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-askpassRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-askpass-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-askpass-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-cavsRocky

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-cavsRed Hat / RHEL

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-cavs-debuginfoRed Hat / RHEL

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-cavs-debuginfoRocky

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-clientsRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-clientsRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-clients-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-clients-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-debugsourceRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-debugsourceRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-keycatRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-keycatRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-keycat-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-keycat-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-keysignRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

openssh-keysignRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

openssh-keysign-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

openssh-keysign-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

openssh-ldapRed Hat / RHEL

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-ldapRocky

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-ldap-debuginfoRocky

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-ldap-debuginfoRed Hat / RHEL

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

openssh-serverRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-serverRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-server-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-server-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:8.0p1-30.el8_10RHSA-2026:47755

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-sk-dummy-debuginfoRocky

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

openssh-sk-dummy-debuginfoRed Hat / RHEL

Fixed in:0:9.9p1-25.el10_2RHSA-2026:47757

Fixed in:0:9.9p1-9.el9_8RHSA-2026:47756

pam_ssh_agent_authRed Hat / RHEL

Fixed in:0:0.10.3-7.30.el8_10RHSA-2026:47755

Fixed in:0:0.10.4-7.9.el9_8RHSA-2026:47756

pam_ssh_agent_authRocky

Fixed in:0:0.10.3-7.30.el8_10RHSA-2026:47755

Fixed in:0:0.10.4-7.9.el9_8RHSA-2026:47756

pam_ssh_agent_auth-debuginfoRocky

Fixed in:0:0.10.3-7.30.el8_10RHSA-2026:47755

Fixed in:0:0.10.4-7.9.el9_8RHSA-2026:47756

pam_ssh_agent_auth-debuginfoRed Hat / RHEL

Fixed in:0:0.10.3-7.30.el8_10RHSA-2026:47755

Fixed in:0:0.10.4-7.9.el9_8RHSA-2026:47756

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityHigh

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N

Exploit Intelligence

0.09%probability of exploitation in 30 days

1stpercentile

Low risk: more likely to be exploited than 1% of all known CVEs.

References

Vendor Advisory2

Other references4

Related Vulnerabilities

Other CWE-923 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-24974	High	7.5	9.8%	-	Fix
CVE-2025-48999	High	8.8	7.8%	-	Fix
CVE-2021-38487	High	8.2	3.3%	-	Fix
CVE-2019-17440	Critical	10.0	1.7%	-	-
CVE-2022-2663	Medium	5.3	1.5%	-	Fix
CVE-2021-32635	Medium	6.3	1.4%	-	-

Common questions

How do I fix CVE-2026-55655?

Published advisories record a fix for 40 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2026-55655 being actively exploited?

Not that we know of. CVE-2026-55655 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.09% is the estimated probability that it will be exploited in the next 30 days. That is higher than 1% of all scored CVEs.

How severe is CVE-2026-55655?

CVE-2026-55655 has a CVSS v3 base score of 5.0, rated moderate. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-55655 affect?

Published advisories record a fix for openssh (Rocky), openssh (Red Hat / RHEL), openssh-askpass (Rocky), openssh-askpass (Red Hat / RHEL), and 36 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-55655

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-30.