High 8.1Published Oct 15, 2026

CVE-2026-63442OPNsense: Log Forgery via Login Username CRLF in WebGUI Authentication → Pf Table IP Blocking

Updated under an hour ago (2026-10-19 10:10 UTC)

Does this affect you?

It affects opnsense core. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.29%, higher than 20% of scored CVEs.

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Exploited in the last 30 days

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.

CVSS: 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Weakness (CWE): CWE-117
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.29% (percentile 20)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 16, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

opnsense core opnsense:core (from the name)	before 26.1.11	CNA record

References

https://github.com/opnsense/core/security/advisories/GHSA-2v2x-m4j7-76pvx-refsource-confirm
https://github.com/opnsense/core/commit/8bdaad95f405f4587bb83bf35aa652ca493cc2a4x-refsource-misc
https://github.com/opnsense/core/commit/c930ab586ffe2d2e010e5135657e5e054316ff58x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.