What’s Vulnerable › Vulnerabilities

CVE-2026-58051: libssh2 - Free of Uninitialized Pointer in publickey List Cleanup

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-28 · updated 2026-10-25
• Weakness: CWE-908

Description

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.

Affected products

• libssh2: through 1.11.1

References

• https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc
• https://github.com/libssh2/libssh2/blob/master/src/publickey.c
• https://www.vulncheck.com/advisories/libssh2-free-of-uninitialized-pointer-in-publickey-list-cleanup

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