Improper Restriction of Excessive Authentication Attempts in OPNsense - #VU129775
Published: May 5, 2026
Vulnerability identifier: #VU129775
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-307
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass authentication lockout protections.
The vulnerability exists due to improper restriction of excessive authentication attempts in the lockout_handler when processing authentication syslog events containing attacker-controlled usernames. A remote attacker can submit failed login attempts with a crafted username containing a success keyword to bypass authentication lockout protections.
This impacts both the WebGUI and ssh password login paths.
Affected software
OPNsense
Remediation
Install security update from vendor's website.
OPNsense - update to 26.1.7