What is CVE-2026-55200?

CVE-2026-55200 is a high-severity vulnerability in Libssh2, classified under Integer Overflow to Buffer Overflow. CVSS score: 8.1/10. Published 2026-06-17.

How severe is CVE-2026-55200?

High severity. CVSS v3 base score is 8.1 out of 10.

Vulnerability in Libssh2

CVE-2026-55200

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessivel…

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Libssh2 — versions 0, 7acf3dfda80c91c3a8c9f2372546301d4a1a7a8

Weakness classification (CWE)

CWE-680 — Integer Overflow to Buffer Overflow

References

Pull Request (issue-tracking)
Patch Commit (patch)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-55200?: CVE-2026-55200 is a high-severity vulnerability in Libssh2, classified under Integer Overflow to Buffer Overflow. CVSS score: 8.1/10. Published 2026-06-17.
How severe is CVE-2026-55200?: High severity. CVSS v3 base score is 8.1 out of 10.