What the vulnerability does
01Description
The Invisible Anti-Spam & CAPTCHA — reCAPTCHA Alternative for All Forms plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'action' parameter in all versions up to, and including, 5.1 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. The stored payload is written by any unauthenticated admin-ajax.php request whose action value matches an entry in the plugin's explicit-actions list, which is auto-populated for common form builders at activation and requires no authentication gate to reach the save path.
Explanation of Vulnerability in Simple Terms
02Summary
The Invisible Anti-Spam & CAPTCHA plugin for WordPress contains a cross-site scripting (XSS) vulnerability in versions 5.1 and earlier. An attacker can inject malicious scripts that execute in the browsers of site visitors or administrators. The vulnerability requires no authentication and can affect multiple users across the site. Site owners should update to a version newer than 5.1 as soon as a patch is available.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that run in visitors' browsers, potentially stealing credentials or redirecting users.
Potential impact on your site
04Site Impact
Visitors and admins may have their sessions hijacked, credentials stolen, or be redirected to malicious sites.
Conditions required to exploit
05Prerequisites
No authentication required. Attacker can exploit this remotely without user interaction.
Key dates
06Disclosure timeline
August 15, 2026
CVE published
