OPNsense: Stored XSS in Firewall Rules/NAT pages via a HTML-attribute breakout
OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, Firewall Rules and NAT views place stored category names and alias descriptions into HTML title attributes in filter_rule.volt and nat_rule.volt without quote-safe encoding. The response layer uses ENT_NOQUOTES, so a double quote survives and closes the attribute, allowing an event-handler attribute to be added to the existing span. A user with Firewall Categories or Firewall Alias Edit privileges can store a category name or alias description; the category must be assigned to a filter or NAT rule, or the alias must be referenced by a rule source or destination, and the rule must be saved so the affected tooltip is rendered. Script then executes in the session of an administrator or other user who opens the affected Rules or NAT page. The script can access CSRF material and perform authenticated actions as the victim. This issue is fixed in version 26.1.11.
CVE-2026-58391
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-58391
core
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "opnsense",
"product": "core",
"versions": [
{
"status": "affected",
"version": "< 26.1.11"
}
]
}
]- Related CVEs
- CVE-2026-58391
Source reference:
/cveMetadata/cveId
Publisher severity
medium
Source reference: /containers/cna/metrics
- Event
- #42099 · Revision 1
- Added to Heist Feed
- Publisher date