---
id: CVE-2026-58393
title: OPNsense is a FreeBSD based firewall and routing platform
summary: >-
  OPNsense is a FreeBSD based firewall and routing platform. Prior to version
  26.1.11, the OpenVPN Client Specific Override common_name field accepts path
  traversal sequences and openvpn_csc_conf_write() concatenates the value into
  /var/et…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L'
cwe:
  - CWE-22
vendor: opnsense
product: core
affected:
  - core < 26.1.11
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T17:17:25.537'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58393'
references:
  - url: >-
      https://github.com/opnsense/core/commit/3af496143a19153c18b2f9458b2510d58aff2b98
    label: security-advisories@github.com
  - url: >-
      https://github.com/opnsense/core/commit/6101b3e2c90482111f420a47775c14a447441a72
    label: security-advisories@github.com
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-2m9v-p7r9-gfcw'
    label: security-advisories@github.com
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-2m9v-p7r9-gfcw'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-15T16:07:43.427308Z'
ingestedAt: '2026-10-15T16:13:11.536Z'
---

## Overview

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the OpenVPN Client Specific Override common_name field accepts path traversal sequences and openvpn_csc_conf_write() concatenates the value into /var/etc/openvpn-csc/<vpnid>/<common_name> without normalization or a basename check. The affected event handlers are client_connect.php and user_pass_verify.php. An authenticated user with Client Specific Override privileges can store the traversal value, and a matching OpenVPN client-connect or authentication event causes a generated CSO file to be written outside the intended directory. The file content is generated OpenVPN configuration rather than arbitrary bytes, and practical exploitation requires the attacker to cause a matching common name or username to be processed. This issue is fixed in version 26.1.11.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.