---
id: CVE-2026-49131
title: >-
  OPNsense before 26.1.9 contains a stored cross-site scripting vulnerability
  that allows authenticated attackers with firewall rule management privileges
  to inject arbitrary HTML or JavaScript by embedding payloads in the firewall
  rule de…
summary: >-
  OPNsense before 26.1.9 contains a stored cross-site scripting vulnerability
  that allows authenticated attackers with firewall rule management privileges
  to inject arbitrary HTML or JavaScript by embedding payloads in the firewall
  rule de…
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
published: '2026-08-03'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T20:32:21.400'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49131'
references:
  - url: 'https://docs.opnsense.org/releases/CE_26.1.html#june-02-2026'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/opnsense/core/commit/b11d6b340716e240868ab19a369e058a46f0876f
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/opnsense-stored-xss-via-firewall-rule-description-field
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00165
epssPercentile: 0.06211
ingestedAt: '2026-09-16T21:05:36.832Z'
---

## Overview

OPNsense before 26.1.9 contains a stored cross-site scripting vulnerability that allows authenticated attackers with firewall rule management privileges to inject arbitrary HTML or JavaScript by embedding payloads in the firewall rule description field via the filter API endpoint. The unsanitized description value is persisted and later rendered through the default cell formatter in opnsense_bootgrid.js, which assigns raw cell content to innerHTML, causing injected scripts to execute in the browser of any authenticated user who views the Firewall Rules page, enabling session hijacking or credential theft.

## Remediation

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