CVE-2026-3481: The WP Blockade plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'shortcode' parameter in all versions up to and including...

Description

The WP Blockade plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'shortcode' parameter in all versions up to and including 0.9.14. This is due to insufficient input sanitization and output escaping in the render_shortcode_preview() function. The function receives user input from $_GET['shortcode'], passes it through stripslashes() without any sanitization, and then outputs it directly via echo do_shortcode($shortcode) on line 393. When the input is not a valid WordPress shortcode (e.g., an HTML tag with JavaScript event handlers), do_shortcode() returns it unchanged, and it is reflected into the page without escaping. The endpoint is registered via admin_post_ (not admin_post_nopriv_), meaning it requires the user to be logged in with at minimum a Subscriber-level account. There is no nonce verification or additional capability check. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary web scripts in pages that will execute if they can successfully trick a user into performing an action such as clicking a link.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.25%

16.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

References

Timeline

Published: May 22, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-3481?

The WP Blockade plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'shortcode' parameter in all versions up to and including 0.9.14. This is due to insufficient input sanitization and output escaping in the render_shortcode_preview() function. The function receives user input from $_GET['shortcode'], passes it through stripslashes() without any sanitization, and then outputs it directly via echo do_shortcode($shortcode) on line 393. When the input is not a valid WordPress shortcode (e.g., an HTML tag with JavaScript event handlers), do_shortcode() returns it unchanged, and it is reflected into the page without escaping. The endpoint is registered via admin_post_ (not admin_post_nopriv_), meaning it requires the user to be logged in with at minimum a Subscriber-level account. There is no nonce verification or additional capability check. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject arbitrary web scripts in pages that will execute if they can successfully trick a user into performing an action such as clicking a link.

How severe is CVE-2026-3481?

CVE-2026-3481 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2026-3481?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.