CVE-2026-16145 Invisible Anti-Spam & CAPTCHA <= 5.1 - Unauthenticated Stored Cross-Site Scripting via 'action' Parameter
Unauthenticated attackers can inject arbitrary scripts via the action parameter, leading to stored XSS execution when users visit affected pages.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-16145?
CVE-2026-16145 is a high-severity cross-site scripting vulnerability in matthiasnordwig Invisible Anti-Spam & CAPTCHA — reCAPTCHA Alternative for All Forms, 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 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-16145?
How do I fix CVE-2026-16145?
No fix has been published for CVE-2026-16145 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-16145 being exploited?
There is no known exploitation of CVE-2026-16145 in the wild and no public exploit code.
Sources
Also known as GHSA-9x6r-qjxj-jj37.