# CVE-2026-15826: Auth bypass in User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor

> Unauthenticated attackers can bypass authentication via type confusion to gain administrator access and take over the WordPress site.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-2v77-3rr8-9p3p

## What is CVE-2026-15826?

CVE-2026-15826 is a critical authentication bypass vulnerability in cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-704 (Incorrect Type Conversion or Cast)

## Which versions are affected by CVE-2026-15826?


## How do I fix CVE-2026-15826?

No fix has been published for CVE-2026-15826 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15826 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15826 exists.

Public exploit code:

- CVE-2026-15826, CVE-2026-15748 (github_poc): https://github.com/HORKimhab/CVE-2026-15826-CVE-2026-15748
- User Profile Builder 3.16.4 - Unauthenticated Authentication Bypass (nuclei): http/cves/2026/CVE-2026-15826.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15826 and fix it if it is affected.

What it is: CVE-2026-15826 is a critical authentication bypass vulnerability in cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-15826 exists.

Affected product: cozmoslabs User Profile Builder – Beautiful User Registration Forms, User Profiles & User Role Editor. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15826/ (Markdown: https://insights.sbomify.com/CVE-2026-15826/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15826
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15826
- OSV: https://osv.dev/vulnerability/CVE-2026-15826

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-15826/
Summaries are generated and may contain mistakes; the official description above is the record.