CVE-2025-15661: libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

CSIRTS triage

What

There is a heap buffer over-read vulnerability in sftp_symlink() in sftp.c.

Who is affected

Deployments of libssh2 are affected.

Urgency

Remediation is necessary due to the medium severity of the vulnerability.

Action

Update to the latest version of libssh2.

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 6.5

Published

2026-06-09

Exploitation

Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-15661

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.

• Moderate exploitation riskCVE-2025-156611.0% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 61% of all EPSS-scored CVEs.

Referenced CVEs

Same CVEs, other sources

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

• medium[UPDATE] [medium] libssh2: Vulnerability allows Denial of Service and disclosure of informationcert-bund
• unknownMultiple vulnerabilities in Microsoft Azure Linux (July 7, 2026)cert-fr-avis
• unknownDSA-6365-1 libssh2 - security updatedebian

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