CVE-2026-35388: OpenSSH before 10.3 omits connection multiplexing confirmation for proxy-mode multiplexing sessions.

lowCVSS 2.5CVE-2026-35388

CSIRTS triage

vendor: OpenSSH product: OpenSSHMisconfigurationaffected: before 10.3

What: Connection multiplexing confirmation omitted for proxy-mode multiplexing sessions.
Who is affected: OpenSSH versions prior to 10.3 using connection multiplexing in proxy mode.
Urgency: Low priority with CVSS 2.5; not exploited and limited practical impact.
Action: Update OpenSSH to version 10.3 or later.

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: low — CVSS 2.5
Published: 2026-08-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-35388

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-2026-353880.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-35388	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

high[UPDATE] [high] IBM QRadar SIEM: Multiple vulnerabilitiescert-bund
medium[UPDATE] [medium] OpenSSH: Multiple vulnerabilitiescert-bund
unknownPAN-SA-2026-0009 Informational Bulletin: Impact assessment of OSS CVEs in Prisma SD-WAN ION (Severity: INFORMA…paloalto

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 · 2026-08-20
medium[UPDATE] [medium] OpenSSH: Multiple vulnerabilitiescert-bund · 2026-08-17
high[NEW] [high] OpenSSH: Multiple vulnerabilitiescert-bund · 2026-08-11
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