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.

Data from the CrowdSec community indicates that exploitation of CVE-2025-3605 is highly selective and intelligence-driven. Threat actors use advanced reconnaissance and carefully choose their targets, often as part of sophisticated campaigns or advanced persistent threat operations. Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2025-3605. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

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.