CVE-2026-55200: LIBSSH2

High severity, CVSS 8.3. EPSS: 0.8% chance of exploitation in the next 30 days.

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 excessively large packet_length values to corrupt heap memory and achieve remote code execution.

Affected products

• LIBSSH2 LIBSSH2: version 1.11.1 only

Published 2026-06-17. Last modified 2026-09-17.