Frontend Login and Registration Blocks - Privilege Escalation (CVE-2025-3605)

CVE-2025-3605 is a critical vulnerability in the Frontend Login and Registration Blocks plugin for WordPress that allows unauthenticated attackers to escalate privileges by taking over user accounts, including those of administrators. By exploiting improper identity validation in the plugin, attackers can change any user's email address and subsequently reset their password, leading to full account compromise and potential site takeover.

CrowdSec has been tracking this vulnerability and its exploits since 24th of September 2025.

CrowdSec network observations suggest that most exploitation of CVE-2025-3605 involves focused reconnaissance to identify viable targets. Attackers typically tailor their campaigns based on system exposure and configuration. It is unlikely that a given attack is accidental. Telemetry from the CrowdSec network also shows that exploitation activity for CVE-2025-3605 remains steady week-over-week. Attack volumes are consistent with long-term trends, indicating sustained interest from threat actors. CVE-2025-3605 continues to be an active part of the threat landscape and will likely remain this way for the forseeable future.

Attackers exploit the AJAX endpoint /wp-admin/admin-ajax.php by sending requests with the action=flrblocksusersettingsupdatehandle parameter to change the administrator's email address, enabling privilege escalation through the password reset process.