CVE-2026-15826 PUBLISHED

User Profile Builder <= 3.16.4 - Unauthenticated Authentication Bypass via Type Confusion to Administrator Account Takeover via 'username' Parameter

Assigner: Wordfence
Reserved: 15.07.2026 Published: 15.08.2026 Updated: 15.08.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8

Product Status

Vendor cozmoslabs
Product User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor
Versions Default: unaffected
  • affected from 0 to 3.16.4 (incl.)

Credits

  • Supakiad S. (m3ez) finder

References

Problem Types

  • CWE-704 Incorrect Type Conversion or Cast CWE