CVE-2025-15661

Name	CVE-2025-15661
Description	libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.
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)
References	DSA-6365-1
Debian Bugs	1140401

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
	trixie (security)	1.11.1-1+deb13u1	fixed
	forky	1.11.1-3	vulnerable
	sid	1.11.1-4	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libssh2	source	trixie	1.11.1-1+deb13u1		DSA-6365-1
libssh2	source	(unstable)	1.11.1-4			1140401

Notes

https://github.com/libssh2/libssh2/pull/1705
https://github.com/libssh2/libssh2/pull/1717
Fixed by: https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d