CVE-2026-15826: CWE-704 Incorrect Type Conversion or Cast in cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor
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.
AI Analysis
Technical Summary
CVE-2026-15826 is a critical authentication bypass vulnerability in the User Profile Builder plugin for WordPress (<=3.16.4). The issue stems from the wppb_log_in_user() function calling absint() on the return value of wp_insert_user() before verifying if it is a WP_Error object. When a registration uses a username of 61–70 characters, WordPress core rejects it with a WP_Error, but absint() converts this object to integer 1, bypassing the error check. Consequently, the plugin binds and returns a transient-backed autologin nonce associated with user ID 1 (Administrator), allowing unauthenticated attackers to gain full administrative access to the site.
Potential Impact
Successful exploitation allows unauthenticated attackers to bypass authentication and log in as the Administrator (user ID 1), resulting in complete administrative control over the WordPress site. This compromises confidentiality, integrity, and availability of the affected system.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid using the affected versions (<=3.16.4) of the User Profile Builder plugin or disable the plugin to prevent exploitation.
CVE-2026-15826: CWE-704 Incorrect Type Conversion or Cast in cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor
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.
CVSS v3.1
Score 9.8critical
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-15826 is a critical authentication bypass vulnerability in the User Profile Builder plugin for WordPress (<=3.16.4). The issue stems from the wppb_log_in_user() function calling absint() on the return value of wp_insert_user() before verifying if it is a WP_Error object. When a registration uses a username of 61–70 characters, WordPress core rejects it with a WP_Error, but absint() converts this object to integer 1, bypassing the error check. Consequently, the plugin binds and returns a transient-backed autologin nonce associated with user ID 1 (Administrator), allowing unauthenticated attackers to gain full administrative access to the site.
Potential Impact
Successful exploitation allows unauthenticated attackers to bypass authentication and log in as the Administrator (user ID 1), resulting in complete administrative control over the WordPress site. This compromises confidentiality, integrity, and availability of the affected system.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid using the affected versions (<=3.16.4) of the User Profile Builder plugin or disable the plugin to prevent exploitation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-07-15T13:58:17.387Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a800ddbbf8831d539a96b08
Added to database: 08/15/2026, 06:57:31 UTC
Last enriched: 08/22/2026, 13:21:12 UTC
Last updated: 09/06/2026, 11:42:35 UTC
Views: 179
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