---
id: CVE-2026-23942
title: >-
  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 progr…
summary: >-
  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 progr…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'
cwe:
  - CWE-22
vendor: erlang
product: erlang/otp
affected:
  - 'erlang/otp >= 17.0, < 26.2.5.18'
  - 'erlang/otp >= 27.0, < 27.3.4.9'
  - 'erlang/otp >= 28.0, < 28.4.1'
  - 'erlang/ssh >= 3.0.1, < 5.1.4.14'
  - 'erlang/ssh >= 5.2, < 5.2.11.6'
  - 'erlang/ssh >= 5.5, <= 5.5.1'
patched:
  - erlang/otp 28.4.1
  - erlang/ssh 5.2.11.6
published: '2026-03-13'
updated: '2026-07-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23942'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-23942.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/erlang/otp/commit/27688a824f753d4c16371dc70e88753fb410590b
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/erlang/otp/commit/5ed603a1211b83b8be2d1fc06d3f3bf30c3c9759
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/erlang/otp/commit/9e0ac85d3485e7898e0da88a14be0ee2310a3b28
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://github.com/erlang/otp/security/advisories/GHSA-4749-w85x-hw9h'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-23942'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://www.erlang.org/doc/system/versions.html#order-of-versions'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
epss: 0.00363
epssPercentile: 0.29997
ingestedAt: '2026-07-24T15:30:58.193Z'
---

## Overview

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 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.

## Affected

- `erlang/otp >= 17.0, < 26.2.5.18`
- `erlang/otp >= 27.0, < 27.3.4.9`
- `erlang/otp >= 28.0, < 28.4.1`
- `erlang/ssh >= 3.0.1, < 5.1.4.14`
- `erlang/ssh >= 5.2, < 5.2.11.6`
- `erlang/ssh >= 5.5, <= 5.5.1`

## Remediation

Upgrade past the affected range:

- `erlang/otp 28.4.1`
- `erlang/ssh 5.2.11.6`