CVE-2026-59847: Libssh: libssh: integrity downgrade via openssl aes-gcm tag verification

CSIRTS triage

What

There is an integrity downgrade vulnerability via OpenSSL AES-GCM tag verification.

Who is affected

Deployments of libssh are affected.

Urgency

Remediation is medium urgency due to the potential for integrity issues, though exploitation is not currently reported.

Action

Update to the latest version of libssh to mitigate this issue.

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

Details

Source

Microsoft Security Response Center (INTL · vendor-psirt · site)

Severity

medium — CVSS 5.9

Published

2026-07-14

Exploitation

Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-59847

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-2026-598470.30% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 23% of all scored CVEs.

Referenced CVEs

Same CVEs, other sources

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

• high[NEW] [high] libssh: Multiple vulnerabilitiescert-bund
• mediumCVE-2026-59847: A flaw was found in libssh. Incorrect AES-GCM finalization checks in builds using the OpenSSL …nvd

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