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CVE-2026-58390

HIGH 8

Published 2026-10-15 · Last modified 2026-10-20

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.

ELEVATED IMPACT

Severe if exploited (CVSS 8), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.6%chance of exploitation in 30 days · 49th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

8CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ⚠User interaction: A user must take an action (click / open a file)
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors Opnsense

Products Core

Weakness (CWE)

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

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

References and research data (JSON)

All CVSS metrics

  • HIGH 8 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H
  • HIGH 8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H

References

Exploit-tagged references (not proof of a PoC)

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS