Authentication Bypass Vulnerability in User Profile Builder Plugin for WordPress

CVE-2026-15826

What is CVE-2026-15826?

CVE-2026-15826 is a critical authentication bypass vulnerability found in the User Profile Builder plugin for WordPress. This plugin is designed to facilitate user registration and profile management on WordPress sites, providing site administrators with various functionalities for handling user accounts. The vulnerability arises in versions up to and including 3.16.4 due to a flaw in the wppb_log_in_user() function, specifically when handling registration submissions that contain usernames of 61 to 70 characters. The function incorrectly processes the response from wp_insert_user() by coercing a potential error state into an integer before proper error checking. As a result, this oversight allows unauthenticated attackers to circumvent normal authentication checks, granting them the ability to log in as the site's Administrator (user ID 1) and thereby gain complete control over the site.

Potential impact of CVE-2026-15826

1. Full Administrative Access: Attackers can exploit this vulnerability to log in as the site's Administrator, potentially allowing them to change settings, delete content, or install malicious plugins, compromising the integrity of the entire website.

2. Data Breach Risk: With administrative rights, attackers can access sensitive user data stored within the site, leading to unauthorized information dissemination, privacy violations, and legal ramifications for the compromised organization.

3. Loss of Trust and Reputation: The successful exploitation of this vulnerability can result in operational disruptions, loss of client trust, and reputational damage to the organization, impacting customer relationships and business operations.

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