Description
OPNsense core before 26.7.8 contains a log injection vulnerability that allows unauthenticated attackers to plant victim IP addresses in the lockout_handler by submitting crafted WebGUI login usernames. Attackers can submit usernames like 'Invalid user <victim-ip>' repeatedly to add the victim to the sshlockout table, blocking SSH and WebGUI access and killing its pf states.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| opnsense | core | < 26.7.8 | 26.7.8 |
Advisories 1
- WID-SEC-2026-2177 OPNsense: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 3, 2026
References
- https://github.com/opnsense/core/commit/14f8f7dd1d5f06522d60794a7beeac7adb9eca68 patch
- https://github.com/opnsense/core/commit/2076f2c195bf9537ec220f0e5d6aff998f057410 patch
- https://github.com/opnsense/core/blob/26.7.7/src/opnsense/mvc/app/library/OPNsense/Auth/AuthenticationFactory.php#L232 technical-description
- https://github.com/opnsense/core/blob/26.7.7/src/opnsense/scripts/syslog/lockout_handler#L70 technical-description
- GitHub Security Advisory (GHSA-2v2x-m4j7-76pv) vendor-advisory
- https://abraxaslabs.tech/research/opnsense-lockout-factory-ip third-party-advisory
- https://github.com/opnsense/core product
- VulnCheck Advisory: OPNsense core before 26.7.8 Lockout IP Planting via WebGUI Login Username third-party-advisory