Vulnerability · Published Oct 30, 2026 · Assigned by VulnCheck

CVE-2026-119423OPNsense core before 26.7.8 Lockout IP Planting via WebGUI Login Username

Medium 5.3

In plain English

A medium-severity security flaw in core from opnsense. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.4%top 68.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
opnsense	core	0 – before 26.7.8

Weakness: CWE-117 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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