CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup pa

mediumCVSS 6.5CVE-2026-58051

libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 6.5
Published: 2026-06-28
Last updated: 2026-06-30
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-58051

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-2026-580510.28% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 20% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-58051	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

mediumCVE-2026-58051: libssh2 - Free of Uninitialized Pointer in publickey List Cleanupmsrc

Recent advisories for libssh2

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.

high[UPDATE] [high] libssh2: Multiple vulnerabilitiescert-bund · 2026-07-03
highCVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-su…nvd · 2026-06-28
unknownDSA-6365-1 libssh2 - security updatedebian · 2026-06-25
unknownNCSC-2026-0210 [1.01] [M/H] Vulnerabilities fixed in libssh2 by libsshncsc-nl · 2026-06-24
mediumCVE-2026-55199: libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handlermsrc · 2026-06-09
highCVE-2026-55200: libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.cmsrc · 2026-06-09