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HIGH

CVE-2026-63442

CVSS v3

8.1

HIGH

EPSS Score

—

exploit probability

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-63442 yet.

Full record on NVD

Description

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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Published
2026-10-15
Last Modified
2026-10-15

Frequently asked questions

What is 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.

Is CVE-2026-63442 actively exploited?

Active exploitation of CVE-2026-63442 has not been confirmed.

What is the CVSS score for CVE-2026-63442?

CVE-2026-63442 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

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