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 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.

CVSS 4.0

8.3CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

6.5CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS

0.3% chance of exploitation in the next 30 days; higher than 19% of CVEs (scores of 2026-10-25)

CWE

CWE-908

Published

2026-06-28

Modified

2026-10-25

Record from

the NVD, synced 2026-10-25

Affected

• libssh2:libssh2

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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