CVE-2026-16145
Received Received - Intake

Stored XSS in Invisible Anti-Spam & CAPTCHA WordPress Plugin

Publication date: 2026-08-15

Last updated on: 2026-08-15

Assigner: Wordfence

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.

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Meta Information

Published
2026-08-15
Last Modified
2026-08-15
Generated
2026-08-15
AI Q&A
2026-08-15
EPSS Evaluated
N/A
NVD
CVE-2026-16145
EUVD
EUVD-2026-58864

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
wordfence invisible_anti_spam_and_captcha_recaptcha_alternative_for_all_forms to 5.1 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This vulnerability is a Stored Cross-Site Scripting (XSS) flaw in the Invisible Anti-Spam & CAPTCHA WordPress plugin. It allows unauthenticated attackers to inject malicious scripts via the 'action' parameter due to poor input sanitization and output escaping. The payload executes when users access infected pages.

Detection Guidance

Check WordPress sites using the Invisible Anti-Spam & CAPTCHA plugin for suspicious admin-ajax.php requests with the 'action' parameter. Review server logs for unauthenticated POST requests targeting admin-ajax.php with common form builder actions.

Impact Analysis

Unauthenticated attackers could inject scripts that steal user data, hijack sessions, or deface websites. Users visiting compromised pages may have their credentials or sensitive information exposed without their knowledge.

Compliance Impact

This vulnerability could lead to data breaches, violating GDPR and HIPAA requirements for protecting user data. Organizations may face fines or legal penalties if user data is compromised due to this flaw.

Mitigation Strategies

Update the plugin to the latest version if available. If not, disable the plugin immediately. Implement web application firewall rules to block malicious admin-ajax.php requests. Monitor for unauthorized script injections in WordPress pages.

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