Vulnerability in Opnsense Core
CVE-2026-63442
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.
Published .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Opnsense Core — versions < 26.1.11
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-63442?
- CVE-2026-63442 is a high-severity vulnerability in Opnsense Core, classified under Improper Output Neutralization for Logs. CVSS score: 8.1/10. Published 2026-10-15.
- How severe is CVE-2026-63442?
- High severity. CVSS v3 base score is 8.1 out of 10.