CVE-2026-23942

01/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 before OTP 26.2.5.18, OTP 27.3.4.9, and OTP 28.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1. Whether OTP before OTP 17.0, corresponding to ssh before 3.0.1, is affected is unknown.

02/Affected products

erlang: erlang\/otp; erlang: erlang\/ssh

03/References7

• cna.erlef.org/cves/CVE-2026-23942.html Vendor Advisory
• github.com/erlang/otp/security/advisories/GHSA-4749-w85x-hw9h MitigationVendor Advisory
• osv.dev/vulnerability/EEF-CVE-2026-23942 Vendor Advisory
• github.com/erlang/otp/commit/27688a824f753d4c16371dc70e88753fb4… Patch
• github.com/erlang/otp/commit/5ed603a1211b83b8be2d1fc06d3f3bf30c… Patch
• github.com/erlang/otp/commit/9e0ac85d3485e7898e0da88a14be0ee231… Patch
• www.erlang.org/doc/system/versions.html#order-of-versions Product