CVE-2026-3481

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.

CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

References

Other References

https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L360 https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L393 https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L360 https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L393 https://www.wordfence.com/threat-intel/vulnerabilities/id/66950509-ce2a-42fe-a8b2-2a92a1b573c3?source=cve

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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-3481? +

CVE-2026-3481 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-3481? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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