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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Erlang | OTP | 17.0, 3.0.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | erlang | 1:27.3.4.9+dfsg-1 | — |
| Debian 13 | erlang | 1:27.3.4.1+dfsg-1+deb13u2 | — |
| Debian 12 | erlang | 1:25.2.3+dfsg-1+deb12u4 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | erlang | 1:27.3.4.6+dfsg-1ubuntu0.2 | USN-8901-1 |
| Ubuntu 25.10 | erlang | No fix yet | — |
| Ubuntu 24.04 LTS | erlang | 1:25.3.2.8+dfsg-1ubuntu4.8 | USN-8901-1 |
| Ubuntu 22.04 LTS | erlang | 1:24.2.1+dfsg-1ubuntu0.8 | USN-8901-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | erlang | 1:22.2.7+dfsg-1ubuntu0.5+esm3 | USN-8901-1 |
| Ubuntu Pro 18.04 LTS | erlang | 1:20.2.2+dfsg-1ubuntu2+esm4 | USN-8901-1 |
| Ubuntu Pro 16.04 LTS | erlang | 1:18.3-dfsg-1ubuntu3.1+esm4 | USN-8901-1 |
| Ubuntu Pro 14.04 LTS | erlang | 1:16.b.3-dfsg-1ubuntu2.2+esm3 | USN-8901-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | erlang27 | 27.1.3-2.1 | openSUSE-SU-2026:10947-1 |
| openSUSE Leap 16.0 | erlang | 27.1.3-160000.4.1 | openSUSE-SU-2026:20607-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | erlang | 26.2.5.18-1 | — |
Advisories 4
- USN-8901-1 erlang vulnerabilities Ubuntu Security Notices (USN) · Oct 8, 2026
- WID-SEC-2026-0721 Erlang/OTP: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 28, 2026
- openSUSE-SU-2026:10947-1 erlang27-27.1.3-2.1 on GA media SUSE / openSUSE Security Updates · Jun 4, 2026
- openSUSE-SU-2026:20607-1 Security update for erlang SUSE / openSUSE Security Updates · Apr 24, 2026
References
- SFTP root escape via component-agnostic prefix check in `ssh_sftpd` vendor-advisory related
- EEF CNA record for CVE-2026-23942 related
- OSV record EEF-CVE-2026-23942 related
- Erlang/OTP version ordering
- Fix commit 5ed603a in erlang/otp patch
- Fix commit 9e0ac85 in erlang/otp patch
- Fix commit 27688a8 in erlang/otp patch