CVE-2026-87111: User Registration PRO <= 6.2.9 - Unauthenticated Stored Cross-Site Scripting via HTTP Referer Header
The User Registration PRO – Custom Registration Form, Login Form, and User Profile WordPress Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via HTTP Referer Header in all versions up to, and including, 6.2.9 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This vulnerability is present only in the premium build of the plugin and is not present in the free WordPress.org distribution. The nonce required to call the vulnerable AJAX endpoint is localized into the page source of every front-end page for anonymous visitors, making it fully obtainable by unauthenticated attackers.
Affected Software
Event History
Frequently Asked Questions
Which deployments are affected?
Only the premium build of the plugin is affected, in versions up to and including 6.2.9. The free distribution available through WordPress.org is not affected.
Does exploiting this issue require an account or access to a privileged page?
No. An unauthenticated attacker can obtain the required AJAX nonce because it is exposed in the source of every front-end page served to anonymous visitors.
What is the practical impact of a successful exploit?
An attacker can store arbitrary web script through the HTTP Referer header. The script executes when a user visits a page containing the injected content, potentially affecting users in a different security context.