CVE-2026-58051
libssh2 - Free of Uninitialized Pointer in publickey List Cleanup
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| libssh2 libssh2 |
≥ 0; ≤ 1.11.1 (affected, semver)
Other versions: affected |
CNA: VulnCheck |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 6.5 medium |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H | CNA: VulnCheck |
| 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 | CNA: VulnCheck |
Exploit evidence
- https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc
exploit · CNA: VulnCheck
References
- https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-pocCNA: VulnCheck · exploit, third-party-advisory
- https://github.com/libssh2/libssh2/blob/master/src/publickey.cCNA: VulnCheck · product
- https://www.vulncheck.com/advisories/libssh2-free-of-uninitialized-pointer-in-publickey-list-cleanupCNA: VulnCheck · third-party-advisory
- https://cert-portal.siemens.com/productcert/html/ssa-457936.htmlADP: siemens-SADP
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