CVE-2026-49131: OPNsense < 26.1.9 Stored XSS via Firewall Rule Description Field
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 opnsensebootgrid.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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
opnsenseto a version that resolves this vulnerability.Fixed in 26.1.9 - Compensating control
Restrict Firewall rule management privileges to only trusted administrators so authenticated attackers cannot inject payloads via the firewall rule description field (filter API endpoint).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-49131?
The severity of CVE-2026-49131 is medium with a CVSS score of 5.4.
How do I fix CVE-2026-49131?
To fix CVE-2026-49131, upgrade OPNsense to version 26.1.9 or later.
What type of vulnerability is CVE-2026-49131?
CVE-2026-49131 is a stored cross-site scripting (XSS) vulnerability.
Who is affected by CVE-2026-49131?
Authenticated users with firewall rule management privileges in OPNsense versions prior to 26.1.9 are affected by CVE-2026-49131.
What can an attacker do with CVE-2026-49131?
An attacker can inject arbitrary HTML or JavaScript via the firewall rule description field, potentially compromising the application.