CVE-2026-58390 — OPNsense: Stored XSS to root RCE via OpenVPN client common_name in status views
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Opnsense Core).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 8.0 | CVSS 3.1 | High | 1.3 | 6.0 | security-advisories@github.com via NIST National Vulnerability Database |
| 8.0 | CVSS 3.1 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Monitor CSP violation reports and script payloads in reflected parameters.
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Deferred
- Affected products added · opnsense/core
- Record published
- CVSS changed · 8.0
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 15, 2026 – Oct 15, 2026
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
3 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-71490 OPNsense: Direct comma-separated user privileges bypass OPNsense MVC read-only write protection 11h
- High CVE-2026-63442 OPNsense: Log Forgery via Login Username CRLF in WebGUI Authentication → Pf Table IP Blocking 11h
- Medium CVE-2026-58394 OPNsense: Stored XSS in Administration Settings via Certificate Description 11h
- Medium CVE-2026-58393 OPNsense: OpenVPN Client Specific Override common_name allows path traversal in generated CSO files 11h
- Medium CVE-2026-58391 OPNsense: Stored XSS in Firewall Rules/NAT pages via a HTML-attribute breakout 11h
- Medium CVE-2026-58392 OPNsense: Stored XSS in Services: NTP GPS 11h
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-58390 is "OPNsense: Stored XSS to root RCE via OpenVPN client common_name in status views", rated High. It affects Core (Opnsense); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.0 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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