CVE-2026-27836 phpMyFAQ Allows Unauthenticated Account Creation via WebAuthn Prepare Endpoint

What is CVE-2026-27836?

CVE-2026-27836 is a high-severity missing authorization vulnerability in Phpmyfaq Phpmyfaq, published on 27 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

phpMyFAQ is an open source FAQ web application. Prior to version 4.0.18, the WebAuthn prepare endpoint (`/api/webauthn/prepare`) creates new active user accounts without any authentication, CSRF protection, captcha, or configuration checks. This allows unauthenticated attackers to create unlimited user accounts even when registration is disabled. Version 4.0.18 fixes the issue.

Weakness: CWE-862

Which versions are affected by CVE-2026-27836?

2 open source packages ship an affected version, including thorsten/phpmyfaq. It affects 1 product.

Products include Phpmyfaq Phpmyfaq.

How do I fix CVE-2026-27836?

Upgrade thorsten/phpmyfaq to 4.0.18 or later.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-27836 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27836 exists.

Other vulnerabilities in Phpmyfaq Phpmyfaq

• CVE-2023-0310 Cross-site Scripting (XSS) - Stored in thorsten/phpmyfaq Critical 9.8
• CVE-2022-4407 Cross-site Scripting (XSS) - Reflected in thorsten/phpmyfaq Critical 9.8
• CVE-2017-11187 Security feature bypass in n/a Critical 9.8
• CVE-2026-76213 phpMyFAQ before 4.1.7 2FA Brute-Force via Session-Scoped Throttle Critical 9.1
• CVE-2026-76214 phpMyFAQ before 4.1.7 WebAuthn Replay Attack via Challenge Critical 9.1

All Phpmyfaq Phpmyfaq vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-w22q-m2fm-x9f4.