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Critical · 9.8 Scanner template Public exploit CVE-2026-15826 EUVD-2026-59593GHSA-2v77-3rr8-9p3p

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

Published Aug 15, 2026 · Updated Aug 17, 2026 · Assigned by Wordfence

Vendor: Cozmoslabs Product: User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor Category: Web / CMS

Description

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.

Affected products

VendorProductAffectedFixed
cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor ≤ 3.16.4 —

Public exploits

Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.

Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.

GitHub 1 repository

Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.

Automated scanner template

A ready-made Nuclei template detects this vulnerability automatically. Vulnerabilities with public scanner templates are typically probed across the internet soon after the template appears — exposed systems should be patched first.

Source: projectdiscovery/nuclei-templates (MIT) — updated daily. Only links are listed.

References