OPNsense: Stored XSS to root RCE via OpenVPN client common_name in status views (CVE-2026-58390)

What is affected, what to do

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.

Update Opnsense Core to version 26.1.11.

Affected

• Opnsense Core lt *..26.1.11

Fixed in

• Opnsense Core 26.1.11

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Metrics

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2

NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

Read in glossary

High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.

CRA

The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

Read in glossary

From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.

ISO/IEC 27001

ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

Read in glossary

Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

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.

Source: cvelistv5, NVD (NIST)

Vendors and products

• Opnsense Core

Weakness classes (CWE)

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

  Base

  The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

  Entry at MITRE CWE-79

References & sources

• github.comopnsense/core/security/advisories/GHSA-26cj-h9rj-g5pfx_refsource_CONFIRM
• github.comopnsense/core/commit/11180daf579879d84d91a7fbea7a59320bc80868x_refsource_MISC
• github.comopnsense/core/commit/e7b2ac8093f804bef8eb88dfa9a0d99fad00c12bx_refsource_MISC

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

1. 20.10.2026Record modifiedCISA ADP

   CISA assessment (SSVC): exploitation: proof of concept, automatable: no

   New references:

   • https://github.com/opnsense/core/security/advisories/GHSA-26cj-h9rj-g5pf
   Show 2 original changes

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   Reference	added	—	https://github.com/opnsense/core/security/advisories/GHSA-26cj-h9rj-g5pf
   SSVC assessment	added	—	{"id":"CVE-2026-58390","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-20T02:43:46.164395Z"}

   Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

2. 15.10.2026ReceivedGitHub

   CVSS V3.1: AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

   Weakness type: CWE-79

   Description added or changed

   New references:

   • https://github.com/opnsense/core/commit/11180daf579879d84d91a7fbea7a59320bc80868
   • https://github.com/opnsense/core/commit/e7b2ac8093f804bef8eb88dfa9a0d99fad00c12b
   • https://github.com/opnsense/core/security/advisories/GHSA-26cj-h9rj-g5pf
   Show 7 original changes

   Individual changes of this event as published by NVD

   Type	Action	Before	After
   Description	added	—	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.
   CVSS	added	—	AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
   Weakness type (CWE)	added	—	CWE-79
   Affected versions (publisher)	added	—	New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/58xxx/CVE-2026-58390.json">CVE-2026-58390</a>
   Reference	added	—	https://github.com/opnsense/core/commit/11180daf579879d84d91a7fbea7a59320bc80868
   Reference	added	—	https://github.com/opnsense/core/commit/e7b2ac8093f804bef8eb88dfa9a0d99fad00c12b
   Reference	added	—	https://github.com/opnsense/core/security/advisories/GHSA-26cj-h9rj-g5pf

   Source identifier: security-advisories@github.com