CVE-2026-15826: The User Profile Builder plugin for WordPress is vulnerable to Authentication Bypass via Type
Source GCVE Database
Not known to be exploited · public detection template (Nuclei) · CVSS 9.8 Critical.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 3.9% chance of exploitation in 30 days – higher than 90% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 2026
Detectable: evidence found.
nuclei template: User Profile Builder 3.16.4 - Unauthenticated Authentication Bypass
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| cozmoslabsUser Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor | Affected
| Fixed in– |
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-15826 (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/features/functions.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/class-formbuilder.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/default-fields/username/username.php (opens in a new tab)
- plugins.trac.wordpress.org/browser/profile-builder/tags/3.16.4/front-end/default-fields/username/username.php (opens in a new tab)
- plugins.trac.wordpress.org/changeset/3609855/profile-builder (opens in a new tab)
- wordfence.com/threat-intel/vulnerabilities/id/9f606fba-f779-42ea-a160-6c3b20dc5e79?source=cve (opens in a new tab)