CVE-2026-15826 json
User Profile Builder <= 3.16.4 - Unauthenticated Authentication Bypass via Type Confusion to Administrator Account Takeover via 'username' Parameter
published 2026-08-15 2 mo ago modified 2026-08-20 2 mo ago also EUVD-2026-59593
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 3.9%
- EPSS 3.9% chance of exploitation in 30 days, percentile 90%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
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.
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 2 mo ago
Exploit prediction
3.90% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template User Profile Builder 3.16.4 - Unauthenticated Authentication Bypass nuclei detection template
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected products
- cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor
Classification
- Weakness
-
- CWE-704 Incorrect Type Conversion or Cast
- Technology feeds
References
- wordfence.com /threat-intel/vulnerabilities/id/9f606fba-f779-42ea-a160-6c3b20dc5e79?source=cve
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/default-fields/username/username.php#L28
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/default-fields/username/username.php#L49
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php#L742
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php#L364
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php#L262
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/features/functions.php#L1481
- plugins.trac.wordpress.org /browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php#L945
- plugins.trac.wordpress.org /changeset/3609855/profile-builder
Sources
- CVE List CVE-2026-15826
- NVD CVE-2026-15826
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.