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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
<h3>CVE-2026-23942</h3> 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…
<h3>CVE-2026-23942</h3>
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
| Vendor | Product | Version |
|---|---|---|
OTP-17.0, OTP-18.0, OTP-18.0-rc1, OTP-19.0, OTP-19.0-rc1, OTP-19.0-rc2, OTP-20.0, OTP-20.0-rc1, OTP-20.0-rc2, OTP-21.0, OTP-21.0-rc1, OTP-21.0-rc2, OTP-22.0, OTP-22.0-rc1, OTP-22.0-rc2, OTP-22.0-rc3, |
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | fixed | 1:25.2.3+dfsg-1+deb12u4 |
| debian | bullseye | fixed | 1:23.2.6+dfsg-1+deb11u4 |
| debian | forky | fixed | 1:27.3.4.9+dfsg-1 |
| debian | sid | fixed | 1:27.3.4.9+dfsg-1 |
| debian | trixie | fixed | 1:27.3.4.1+dfsg-1+deb13u2 |
| sles | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| erlang | erlang\/otp | {"startIncluding":"17.0","endExcluding":"26.2.5.18"} | 26.2.5.18 |
| erlang | erlang\/ssh | {"startIncluding":"3.0.1","endExcluding":"5.1.4.14"} | 5.1.4.14 |
References
- https://github.com/erlang/otp/security/advisories/GHSA-4749-w85x-hw9h
- https://cna.erlef.org/cves/CVE-2026-23942.html
- https://osv.dev/vulnerability/EEF-CVE-2026-23942
- https://www.erlang.org/doc/system/versions.html#order-of-versions
- https://github.com/erlang/otp/commit/27688a824f753d4c16371dc70e88753fb410590b
- https://github.com/erlang/otp/commit/9e0ac85d3485e7898e0da88a14be0ee2310a3b28
- https://github.com/erlang/otp/commit/5ed603a1211b83b8be2d1fc06d3f3bf30c3c9759
- https://security-tracker.debian.org/tracker/CVE-2026-23942
- https://www.suse.com/security/cve/CVE-2026-23942.html
CWEs
CWE-22
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.