---
id: CVE-2026-58392
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 NTP GPS page stores the operator-supplied initcmd value in base64
  form, applies legacy_html_escape_form_data() to the encoded string, and then
  uses …
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: opnsense
product: core
affected:
  - core < 26.1.11
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T16:18:18.167'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58392'
references:
  - url: >-
      https://github.com/opnsense/core/commit/a92d9514b5436c868f8f97138ebed507f6de423c
    label: security-advisories@github.com
  - url: >-
      https://github.com/opnsense/core/commit/ed04a154dc40967541be1388e9134e451be4199e
    label: security-advisories@github.com
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-h793-67jm-j4m5'
    label: security-advisories@github.com
  - url: 'https://hackerask.com/posts/opnsense'
    label: security-advisories@github.com
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-h793-67jm-j4m5'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-15T15:54:50.680359Z'
ingestedAt: '2026-10-15T16:13:10.832Z'
---

## Overview

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the NTP GPS page stores the operator-supplied initcmd value in base64 form, applies legacy_html_escape_form_data() to the encoded string, and then uses base64_decode() to decode the value directly into the GPS initialization-command textarea in src/www/services_ntpd_gps.php. Because decoding occurs after escaping, stored HTML remains unescaped at the output sink. A user with page-services-ntp-gps privilege can store a value that closes the textarea, and script executes in the session of any user who later opens the GPS page. The script can read CSRF material and perform authenticated actions, including actions available to an administrator. This issue is fixed in version 26.1.11.

## Remediation

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