CVE-2026-63442
8.1HighPublished 15 Oct 2026 · NVD status: Deferred · AI triage by gemini-3.8-flash
- Attack vector
- Adjacent network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Impact
- High impact on integrity, availability
- Weakness
- CWE-117
Impact
Unauthenticated attackers with network access to the WebGUI can inject log lines to arbitrarily block target IPs via the sshlockout table or bypass brute-force login protections. This allows denial-of-service against administrative, DNS, gateway, or monitoring addresses and enables unrestricted credential guessing.
Root cause
The WebGUI login form accepts unescaped CRLF characters in the username field, allowing log injection into the syslog-ng lockout handler that interprets forged lines as real authentication events.
Affected systems
OPNsense prior to version 26.1.11
CVSS v3.1 · CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Fix & remediation
Upgrade to OPNsense 26.1.11. As an interim workaround, restrict or disable network access to the WebGUI login interface using firewall rules so only trusted management hosts can reach it.
$ opnsense-updateAI-suggested. Run it in staging first and check it against the vendor advisory. Why?
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.