VulnerabilityDeferred

CVE-2026-15826

The User Profile Builder plugin for WordPress is vulnerable to Authentication Bypass via Type Confusion in versions up to, and including, 3.16.4.

CRITICAL 9.8EPSS 3.91%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (3.91%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 3.91% probability · 90th percentile
CISA KEV: Not listed
Weakness: CWE-704
Source: security@wordfence.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.