Stored cross-site scripting in OPNsense OpenVPN status views
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- High
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
OPNsense core before 26.1.11 places OpenVPN client common_name values into HTML attributes without encoding, causing stored cross-site scripting (CWE-79). An authenticated VPN client with a double quote in its backend username injects an event handler that runs in the administrator's session on the dashboard or status page. It requires username-as-common-name with RADIUS or LDAP authentication. The advisory shows the script can reset the root password and run commands as root.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the CNA
OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the OpenVPN connection-status dashboard widget in src/opnsense/www/js/widgets/OpenVPNClients.js and the connection-status view place a client common_name into data-common-name attributes without quote-safe encoding. Exploitation requires an OpenVPN server configured with username-as-common-name and RADIUS or LDAP authentication, plus the ability to provision or self-register a valid backend username containing a double quote; deployments where the same administrator controls both the identity backend and firewall do not cross a separate trust boundary. An authenticated client using that username can close the attribute and add an event handler, while the local user database is not affected because its username validator rejects quotes. Script executes in an administrator's session when the administrator opens the dashboard or connection-status page and the injected event is triggered; the demonstrated payload used pointer movement over the client row rather than unconditional page-load execution. The advisory demonstrates that the script can read config.xml, invoke privileged APIs, reset the root password, and obtain root command execution. This issue is fixed in version 26.1.11.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
Upgrade OPNsense core to version 26.1.11 or later, which fixes this issue.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
- Fix · CNA core (opnsense) Fixed in 26.1.11
Timeline
- 2026-10-16 Threatist record created from CVE-2026-58390
- 2026-10-16 Priority changed: MEDIUM → LOW
- 2026-10-20 CISA SSVC decision points changed
- 2026-10-20 Priority changed: LOW → HIGH
References
More opnsense vulnerabilities
- TI-2023-20247 A command injection vulnerability in the component /api/cron/settings/setJob/ of OPNsense… CVSS 3.1CRITICAL 9.8
- TI-2023-20243 Insecure permissions in the configuration directory (/conf/) of OPNsense Community… CVSS 3.1CRITICAL 9.8
- TI-2023-20240 A command injection vulnerability in the component diag_backup.php of OPNsense Community… CVSS 3.1CRITICAL 9.8
- TI-2023-11947 DECISO OPNsense 23.1 does not impose rate limits for authentication, allowing attackers… CVSS 3.1CRITICAL 9.8
- TI-2026-74819 Path traversal in OPNsense GeoIP importer allows root code execution CVSS 3.1CRITICAL 9.9
- TI-2023-20246 /ui/cron/item/open in the Cron component of OPNsense Community Edition before 23.7 and… CVSS 3.1CRITICAL 9.6
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences