CVE-2026-23942: SFTP root escape via component-agnostic prefix check in ssh_sftpd
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.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23942?
CVE-2026-23942 has a significant severity due to its potential for causing path traversal vulnerabilities in affected software versions.
How do I fix CVE-2026-23942?
To fix CVE-2026-23942, upgrade to Erlang OTP version 28.4.2 or later, and ensure your Erlang SSH implementation is updated accordingly.
Which software is affected by CVE-2026-23942?
CVE-2026-23942 affects Erlang OTP versions between 17.0 and 28.4.1, and Erlang SSH versions between 3.0.1 and 5.5.1.
What type of vulnerability is CVE-2026-23942?
CVE-2026-23942 is classified as a Path Traversal vulnerability that allows unauthorized access to restricted directories.
Is there a known exploit for CVE-2026-23942?
As of now, there is no publicly disclosed exploit for CVE-2026-23942, but it poses serious security risks if unpatched.