CVE-2026-63442
HIGHDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 21% of all known CVEs.
References
Related Vulnerabilities
Other CWE-117 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2021-43410 | Medium | 5.3 | 2.5% | - | Fix |
| CVE-2022-32549 | Medium | 5.3 | 2.4% | - | - |
| CVE-2019-14864 | Medium | 6.5 | 1.9% | - | Fix |
| CVE-2021-42250 | Medium | 6.5 | 1.8% | - | Fix |
| CVE-2024-47083 | High | 7.5 | 1.6% | - | - |
| CVE-2020-25646 | High | 7.5 | 1.4% | - | - |
Common questions
How do I fix CVE-2026-63442?
No published fix for CVE-2026-63442 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-63442 being actively exploited?
Not that we know of. CVE-2026-63442 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 21% of all scored CVEs.
How severe is CVE-2026-63442?
CVE-2026-63442 has a CVSS v3 base score of 8.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-16.