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Public proof of concept

CVE-2026-15826

User Profile Builder <= 3.16.4 - Unauthenticated Authentication Bypass via Type Confusion to Administrator Account Takeover via 'username' Parameter

A public proof of concept exists; no exploitation attested.

  • Published2026-08-15
  • WeaknessCWE-704

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-08-1507:16CVE publishedNVD

Versions per branch

Products declared by the CNA

As Wordfence, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editorother versions: not affected
    Affected
    • ≤ 3.16.4no fix statedsemver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-15

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-15826 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

read 2026-11-01 01:02 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-08-15
Last Modified
2026-08-20
NVD status
Deferred
GitHub Advisory
GHSA-2v77-3rr8-9p3p

Frequently asked questions

What is 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. 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.

Is CVE-2026-15826 actively exploited?

Active exploitation of CVE-2026-15826 has not been confirmed. Its EPSS score was 3.9% on 2026-11-13, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-15826?

CVE-2026-15826 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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Sources for this record