CVE-2026-55200

Name	CVE-2026-55200
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libssh2 (PTS)	bullseye	1.9.0-2+deb11u1	vulnerable
	bookworm	1.10.0-3	vulnerable
	trixie	1.11.1-1	vulnerable
	sid, forky	1.11.1-3	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libssh2	source	(unstable)	(unfixed)

https://github.com/libssh2/libssh2/pull/2052
Fixed by: https://github.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8