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

Status: published. Published: 2026-06-28. Updated: 2026-11-10.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- libssh2 / libssh2: ≥ 0; ≤ 1.11.1 (affected, semver). Source: CNA: VulnCheck
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP
- Siemens / SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0): ≥ V3.1.7; < * (affected, custom). Source: ADP: siemens-SADP

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H; source: CNA: VulnCheck

- CVSS 4.0: 8.3 (high); CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.28% as of 2026-11-09; percentile 20.22%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-908

## Exploit evidence

- exploit: https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc (CNA: VulnCheck)

## References

- https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc (CNA: VulnCheck; exploit, third-party-advisory)

- https://github.com/libssh2/libssh2/blob/master/src/publickey.c (CNA: VulnCheck; product)

- https://www.vulncheck.com/advisories/libssh2-free-of-uninitialized-pointer-in-publickey-list-cleanup (CNA: VulnCheck; third-party-advisory)

- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (ADP: siemens-SADP)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-58051; retrieved 2026-11-10; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-58051; retrieved 2026-11-10; source updated Not reported

Revision: 4f36a2d06e668c18e01299b550565891088999aea44cd03eceaa6d794679c043

Canonical: https://y2.dev/cve/CVE-2026-58051

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