CVE-2025-5372

Name	CVE-2025-5372
Description	A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1108407

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libssh (PTS)	bullseye (security), bullseye	0.9.8-0+deb11u1	vulnerable
	bookworm, bookworm (security)	0.10.6-0+deb12u1	vulnerable
	sid, trixie	0.11.2-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libssh	source	(unstable)	0.11.2-1			1108407

Notes

[bookworm] - libssh <no-dsa> (Minor issue)
[bullseye] - libssh <postponed> (Minor issue)
https://www.libssh.org/security/advisories/CVE-2025-5372.txt
Fixed by: https://git.libssh.org/projects/libssh.git/commit/?id=a9d8a3d44829cf9182b252bc951f35fb0d573972 (libssh-0.11.2)