CVE-2026-23942

Name	CVE-2026-23942
Description	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 until OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 until 5.5.1, 5.2.11.6 and 5.1.4.14.
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)
Debian Bugs	1130912

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
erlang (PTS)	bullseye	1:23.2.6+dfsg-1+deb11u1	vulnerable
	bullseye (security)	1:23.2.6+dfsg-1+deb11u3	vulnerable
	bookworm	1:25.2.3+dfsg-1+deb12u3	vulnerable
	bookworm (security)	1:25.2.3+dfsg-1+deb12u1	vulnerable
	trixie	1:27.3.4.1+dfsg-1+deb13u1	vulnerable
	forky, sid	1:27.3.4.8+dfsg-1	vulnerable

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
erlang	source	(unstable)	(unfixed)			1130912

Notes

https://github.com/erlang/otp/security/advisories/GHSA-4749-w85x-hw9h
Fixed by: https://github.com/erlang/otp/commit/27688a824f753d4c16371dc70e88753fb410590b (OTP-28.4.1)
Fixed by: https://github.com/erlang/otp/commit/9e0ac85d3485e7898e0da88a14be0ee2310a3b28 (OTP-27.3.4.9)
Fixed by: https://github.com/erlang/otp/commit/5ed603a1211b83b8be2d1fc06d3f3bf30c3c9759 (OTP-26.2.5.18)