---
id: CVE-2026-63442
title: OPNsense is a FreeBSD based firewall and routing platform
summary: >-
  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…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-117
vendor: opnsense
product: core
affected:
  - core < 26.1.11
published: '2026-10-15'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T16:18:19.157'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-63442'
references:
  - url: >-
      https://github.com/opnsense/core/commit/8bdaad95f405f4587bb83bf35aa652ca493cc2a4
    label: security-advisories@github.com
  - url: >-
      https://github.com/opnsense/core/commit/c930ab586ffe2d2e010e5135657e5e054316ff58
    label: security-advisories@github.com
  - url: 'https://github.com/opnsense/core/security/advisories/GHSA-2v2x-m4j7-76pv'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-10-15T16:13:11.454Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.