CVE-2026-55655: Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions

mediumCVSS 5CVE-2026-55655

CSIRTS triage

vendor: Red Hat product: OpenSSHOther

What: Local man-in-the-middle attacks can occur via abstract unix socket pre-binding in OpenSSH client versions.
Who is affected: Users of Red Hat Enterprise Linux OpenSSH client are affected.
Urgency: Medium urgency for remediation due to a CVSS score of 5 and potential for exploitation.
Action: Update OpenSSH client to the latest version to mitigate this vulnerability.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55655

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-556550.09% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 1% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-55655	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[UPDATE] [medium] OpenSSH: Multiple vulnerabilitiescert-bund

Recent advisories for Openssh

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEW] [medium] OpenSSH: Multiple vulnerabilitiescert-bund · 2026-07-10
medium[UPDATE] [medium] OpenSSH: Multiple vulnerabilitiescert-bund · 2026-07-09
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medium[UPDATE] [medium] OpenSSH: Multiple vulnerabilitiescert-bund · 2026-07-08
highCVE-2026-60002: ssh in OpenSSH before 10.4 can have a use-after-free when a server changes its host key during…nvd · 2026-07-08
mediumCVE-2026-60001: sshd in OpenSSH before 10.4 does not always honor the minimum authentication delay.nvd · 2026-07-08