Description
OPNsense is a FreeBSD based firewall and routing platform. Prior to 26.1.7, a logic flaw in the OPNsense lockout_handler allows an unauthenticated attacker to continuously reset the authentication failure counter for their IP address. By interjecting a crafted username containing a success keyword ("Accepted" or "Successful login") between normal brute-force attempts, an attacker can prevent the failure counter from ever reaching the lockout threshold. This vulnerability is fixed in 26.1.7.
References (2)
Core 2
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/opnsense/core/security/advisories/GHSA-h3vx-4q27-rc42
Various Sources
https://gist.github.com/sopex/b9786e72e2a5d9b1bbd81ed8477c351b
Scores
CVSS v3
5.3
EPSS
0.0032
EPSS Percentile
23.3%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-307
Status
published
Products (2)
opnsense/core
< 26.1.7
opnsense/opnsense
< 26.1.7
Published
May 13, 2026
Tracked Since
May 14, 2026