CVE-2026-15826
CriticalCVSS 9.8Summary
The User Profile Builder plugin for WordPress up to version 3.16.4 is vulnerable to authentication bypass via type confusion. The wppb_log_in_user() function calls absint() on the return value of wp_insert_user() before performing an is_wp_error() check. When a registration is submitted with a 61–70 character username, WordPress rejects it with a WP_Error object, but absint() coerces that object to the integer 1, causing the plugin to bind and return a transient-backed autologin nonce tied to user ID 1. This allows unauthenticated attackers to log in as the site's Administrator account (user ID 1), resulting in full administrative takeover.
Risk Assessment
Full administrative takeover of the site by an unauthenticated attacker.
Recommendation
Update the User Profile Builder plugin to a patched version.
Original NVD description (English source)
The User Profile Builder plugin for WordPress is vulnerable to Authentication Bypass via Type Confusion in versions up to, and including, 3.16.4. This is due to the wppb_log_in_user() function calling absint() on the return value of wp_insert_user() before performing an is_wp_error() check — when a registration is submitted with a 61–70 character username, WordPress core rejects it with a WP_Error object, but absint() coerces that object to the integer 1 before the error check can short-circuit execution, causing the plugin to bind and return a transient-backed autologin nonce tied to user ID 1. This makes it possible for unauthenticated attackers to log in as the site's Administrator account (user ID 1), resulting in full administrative takeover of the site.