CVE-2026-63442

What it is

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the unauthenticated WebGUI login usernamefld accepts carriage-return and line-feed characters that survive LOG_AUTH processing through syslog-ng-lockout.conf into the syslog-ng program destination feeding lockout_handler. The consumer's readline() processing treats an injected fragment as a separate authentication event and selects the first syntactically valid IP address from the forged line. An attacker with network access to the login page can forge failure events for another IP, causing that IP to be added to the sshlockout PF table and its active states to be killed, or forge accepted events that reset an attacker's own brute-force counter. This can block administrative, DNS, gateway, or monitoring addresses and can bypass password-guessing lockout without authentication. This issue is fixed in version 26.1.11.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of data tampering, service disruption.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-10-15 16:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-16 18:18 UTC Last updatedMost recent change to the record

Details

Published

2026-10-15 16:18 UTC

Last modified

2026-10-16 18:18 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-117

Record status

Deferred

Attack profile CVSS 3.1 · 8.1

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High