Integer overflow in Libssh2
CVE-2026-58050
libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H.
EPSS exploit prediction
EPSS: 0.004 (36.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 36th percentile — 36.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Libssh2 — versions 0
Weakness classification (CWE)
References
- github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc (exploit, Broken Link, third-party-advisory)
- github.com/libssh2/libssh2/blob/master/src/publickey.c (Product, product)
- www.vulncheck.com/advisories/libssh2-integer-overflow-in-publickey-subsystem-at… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-58050?
- CVE-2026-58050 is a high-severity vulnerability in Libssh2, classified under Integer Overflow or Wraparound. CVSS score: 7.0/10. Published 2026-06-28.
- How severe is CVE-2026-58050?
- High severity. CVSS v3 base score is 7.0 out of 10.