插件名稱	WPBakery 頁面建立器
Type of Vulnerability	Stored Cross-Site Scripting
CVE Number	CVE-2025-11160
Urgency	Low
CVE Publish Date	2025-10-15
Source URL	CVE-2025-11160

WPBakery Page Builder <= 8.6.1 – Stored XSS Vulnerability in Custom JS Module (CVE-2025-11160)

Security researchers have recently uncovered a stored Cross-Site Scripting (XSS) vulnerability in WPBakery Page Builder up to version 8.6.1, catalogued as CVE-2025-11160. This flaw allows attackers with Contributor-level access to exploit the plugin’s Custom JS module, injecting malicious JavaScript that is persistently stored and executed within your site’s context. The vulnerability has been addressed and patched in version 8.7.

At Managed-WP, we are dedicated US security experts actively safeguarding WordPress ecosystems through our Managed Web Application Firewall (WAF) services. We provide comprehensive intelligence and hands-on remediation guidance including:

• A clear, technical explanation of the vulnerability
• Contextual risk assessment tailored for different website types
• Effective detection and cleanup methods you can execute immediately
• Short-term defense strategies including virtual patching and WAF configurations
• Long-term security hardening and continuous monitoring recommendations

This briefing is intended for WordPress site owners, administrators, developers, and security professionals who demand precise, actionable advice—no fluff, just results.

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Executive Summary (TL;DR)

• Vulnerability: Stored XSS in WPBakery’s Custom JS module
• Affected Versions: WPBakery Page Builder versions ≤ 8.6.1
• Fixed in: Version 8.7
• CVE Identifier: CVE-2025-11160
• Required Privilege: Contributor (authenticated low-privileged user)
• CVSS Score: 6.5 (Moderate, depending on site configuration)
• Primary Risk: Persistent JavaScript injection executing in visitors’ browsers, risking session theft, site defacement, redirecting users, and pivoting for wide-scale compromise
• Immediate Remediation: Upgrade to WPBakery 8.7+, review stored content for malicious scripts, apply WAF rules or virtual patches, and restrict contributor capabilities for adding custom JavaScript

Continue reading for our detailed analysis and remediation roadmap.

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Understanding Stored XSS and Its Impact on WordPress

Stored Cross-Site Scripting emerges when malicious JavaScript is saved within a site’s persistent storage—such as posts, pages, or plugin fields—and later delivered to other users in an unsafe manner. Unlike reflected XSS, stored XSS payloads execute whenever the infected content loads, affecting administrators and visitors alike.

This vulnerability is especially severe on WordPress platforms because:

• Injected scripts can hijack administrator sessions by stealing authentication cookies.
• Attackers can embed further malicious code, set persistent redirects, modify visible content, or insert SEO spam.
• Large-scale exploitation is possible by compromising contributor-level accounts and targeting frequently accessed pages like the homepage or admin preview screens.

This particular exploit arises from a plugin feature that permits adding Custom JavaScript. If unchecked, a low-privilege user can embed harmful scripts that run for anyone viewing that content.

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Technical Breakdown: How This Vulnerability Works

• The WPBakery plugin includes a Custom JS module that stores JavaScript code in the site’s database as part of page or post metadata.
• This stored input lacks sufficient sanitization before display, allowing malicious scripts to be executed when the content renders.
• An attacker with Contributor-level privileges can supply a payload, embedding JavaScript that executes in visitors’ browsers—including administrators previewing the site.

Potential Attack Scenarios:

• An attacker injects JavaScript which steals admin cookies and sends them to an external server, enabling full site takeover.
• The malicious script redirects visitors to rogue domains, loads malware, or triggers unwanted actions like cryptomining.
• Dynamic DOM manipulation for spam insertion, form data theft, or further privilege escalation via AJAX.

筆記： Exploitation requires an authenticated Contributor role. Hence, either account compromise or open user registration facilitates the attack vector.

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Who Should Be Concerned?

• Sites running WPBakery Page Builder version 8.6.1 or earlier.
• Sites that allow user registrations or guest content submissions by low-privilege roles.
• Multi-author blogs or platforms with contributor roles enabled.
• Administrators who routinely preview content while logged in, exposing themselves to injected scripts.

If your site meets any of these criteria, this vulnerability warrants immediate attention despite a moderate CVSS rating — the real risk depends on context and attacker access.

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Urgent Actions to Take (First 1-2 Hours)

1. Verify WPBakery Version
     – Check via Dashboard or WP-CLI:

   wp plugin get js_composer --field=version

2. Update to WPBakery 8.7 or Later (if possible)
     – Upgrade immediately if licensing and compatibility permit:

   wp plugin update js_composer --clear-plugins-cache

     – Otherwise, schedule a prompt update while applying temporary mitigations.

3. Restrict Contributor Role Access
     – Temporarily remove or limit contributor permissions, especially related to adding Custom JS modules.
     – Use role management plugins to refine capabilities.
4. Scan for Malicious JavaScript Presence
     – Search posts and postmeta for <script> tags and suspicious event handlers.

   SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%<script%';
   
   SELECT post_id, meta_key FROM wp_postmeta WHERE meta_value LIKE '%<script%';

5. Place Site into Maintenance Mode
     – Limit access while investigating suspected exploitation.
6. Backup Database and Files
     – Create clean, timestamped forensic backups before any remediation.

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Detecting Malicious Payloads: Query Patterns & Recommendations

Monitor for typical script injection markers:

• <script> tags
• Inline event attributes like onerror=, onclick=
• JavaScript commands such as document.cookie, eval(, atob(
• Obfuscated payloads encoded in base64 or other formats

Example SQL & command-line searches:

• SQL queries:

  SELECT ID, post_title FROM wp_posts WHERE post_content REGEXP '<script|onerror=|document\.cookie|eval\(|atob\(';
  
  SELECT post_id, meta_key FROM wp_postmeta WHERE meta_value REGEXP '<script|onerror=|document\.cookie|eval\(|atob\(';

• WP-CLI example:

  wp db query "SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%<script%' LIMIT 50;"

• File scans (uploads, themes, plugins):

  grep -R --line-number -E "<script|document\.cookie|eval|atob|new Image\(|fetch(" wp-content

Document all findings, including affected post IDs, meta keys, and export snapshots for forensic review prior to any cleaning.

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Containment and Remediation Steps

1. Make a fresh backup of your files and database.
2. Remove or sanitize malicious scripts:
     – For post content, strip out offending <script> blocks.
     – For postmeta or plugin-specific fields, clean or delete affected entries.
   Sample WP-CLI cleanup (modify with care):

   wp post update 123 --post_content="$(wp post get 123 --field=post_content | sed 's/<script>malicious.*</script>//g')"

3. Reset credentials and enforce password changes for users with Contributor access, especially if compromise is suspected.
4. Force password resets for all admins and editors recently active.
5. Scan plugins and themes with trusted malware detection tools; verify no backdoors exist.
6. Harden user registrations:
     – Disable open registration if not required.
     – Validate or moderate new Contributor accounts.
7. Review server logs for suspicious POST requests to admin-related endpoints from unfamiliar IPs.
8. If unable to fully remediate, revert to a clean backup, update WPBakery, and strengthen security posture before restoring content.

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Short-Term Protective Measures: WAF Virtual Patching

When immediate plugin updates aren’t feasible, applying WAF rules can provide vital protection by intercepting exploit attempts before execution. Virtual patching effectively blocks malicious payload patterns and reduces risk with minimal downtime.

Recommended WAF rules include:

1. Block POST requests to WPBakery content endpoints if payload contains suspicious JavaScript patterns like <script, document.cookie, eval(， 或者 atob( from non-admin users.
2. Prevent Contributors from submitting content containing script tags or inline event handlers such as onerror=.
3. Filter or sanitize content that includes inline JavaScript events like onclick= 或者 onload=.
4. Rate-limit or block abnormal POST requests to admin endpoints from unknown IP addresses.
5. Deploy strict Content Security Policy headers disallowing inline scripts except from trusted origins:

   Content-Security-Policy: default-src 'self'; script-src 'self' https://trusted.cdn.example; object-src 'none'; base-uri 'self';

Virtual patching succeeds by intercepting malicious inputs prior to storage or execution, reducing the attack surface while comprehensive remediation is underway.

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Long-Term Security Hardening and Best Practices

1. Maintain current versions of all plugins, themes, and the WordPress core.
2. Apply least privilege principles:
     – Restrict post editing and custom JS addition to trusted roles.
     – Prefer Authors with review workflows over Contributors if possible.
3. Implement content moderation workflows for user-generated submissions.
4. Disable or limit modules that allow JavaScript editing for low-privileged users.
5. Ensure output sanitization and escaping at theme/template level using functions like wp_kses, esc_js， 和 esc_html.
6. Utilize nonce-based CSP policies, particularly in admin areas.
7. Audit plugins for raw JS or HTML editing capabilities and minimize their usage.
8. Enforce multi-factor authentication (MFA) for all privileged accounts.
9. Establish continuous monitoring and real-time alerting for suspicious activities in posts and user accounts.
10. Maintain a documented incident response plan covering backup, isolation, restoration, and notification procedures.

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Incident Response Quick Checklist

1. Isolate the site—enable maintenance mode or restrict IP access.
2. Take full forensic backups of files and database.
3. Identify and remove injected scripts and malicious content.
4. Rotate credentials and enforce password resets.
5. Review and remove untrusted or suspicious user accounts.
6. Scan for backdoors and malicious files within themes/plugins/uploads.
7. Compare current site files with trusted baselines (if available).
8. Update all software to the latest fixed versions.
9. Restore from clean backups if remediation is incomplete.
10. Notify stakeholders and comply with any applicable legal breach reporting requirements.

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Why You Should Take This Vulnerability Seriously

While the CVSS score rates this issue as moderate, its real-world danger scales with your site’s setup. Brochure or static sites without contributors face less risk, but community, membership, or multi-author sites are prime targets.

The key threat lies in compromising administrator sessions through injected JavaScript leading to full site takeover. Given many WordPress instances allow user registration or rely on third-party integrations, the path to exploit is often easier than anticipated.

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Monitoring and Logging Recommendations

• Log and alert on any POST requests to admin-ajax.php or REST API endpoints containing suspicious script patterns.
• Monitor changes to postmeta 和 post_content fields for injected scripts.
• Alert on new user registrations immediately followed by script-containing post creations/edits.
• Track outgoing external requests originating from PHP or cron jobs for unusual activity.
• Review WAF logs regularly for blocked exploit attempts and attacker patterns.

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How Managed-WP Safeguards Your WordPress Site

Managed-WP provides a cutting-edge managed WAF and tailored malware mitigation services designed exclusively for WordPress security. Upon disclosure of vulnerabilities like the WPBakery stored XSS, we deploy a layered defense strategy including:

• Rapid virtual patching: precision WAF rules block exploitation attempts and known payload signatures without hindering legitimate traffic.
• Behavioral detection: we detect suspicious content submissions from low-privilege accounts and apply proactive blocks as needed.
• Content scanning: comprehensive malware scanning identifies stored script injections across posts, metadata, and uploads for faster remediation.
• Automated mitigation workflows: managed plan users benefit from content quarantine, sanitization, and real-time admin notifications with actionable next steps.
• Expert guidance: prioritized update instructions, cleanup checklists, and ongoing support ensure thorough site protection.

Our security protocols carefully balance robustness with availability to minimize false positives while maximizing protection.

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Sample Conceptual WAF Rule

This example illustrates a typical WAF rule to mitigate this exploit. Actual implementation depends on your firewall technology.

• Condition:
• Request path contains /wp-admin/, /wp-json/wp/v2/， 或者 admin-ajax.php
• AND request body contains one or more of: <script, onerror=, document.cookie, eval(, atob(
• AND user role is Contributor or not a trusted admin IP
• 行動： Block the request with HTTP 403 Forbidden and log the event.

Warning: Avoid blanket blocking of all script tags if your site legitimately uses inline scripts. Carefully tune and test rules in monitoring mode before enforcing.

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Step-by-Step Update & Remediation Roadmap

1. Immediate (0–1 hour):
     – Identify WPBakery version.
     – If ≤ 8.6.1, place site in maintenance mode if high-risk.
2. Virtual Patch Deployment (0–4 hours):
     – Enable WAF rules detecting script injection attempts.
     – Implement Content Security Policy to restrict inline scripts.
3. Update (0–24 hours):
     – Upgrade WPBakery to 8.7+.
     – Update all plugins and core, monitor for compatibility issues.
4. Cleanup (0–48 hours):
     – Scan and remove injected JavaScript.
     – Rotate passwords and assess user accounts.
5. Hardening (48–72 hours):
     – Implement MFA.
     – Restrict contributor capabilities.
     – Establish continuous monitoring and alerting.
6. Post-Incident Review:
     – Document the incident timeline and improvements.
     – Adjust user, plugin, and security policies accordingly.

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常見問題解答

Q: If I do not have Contributor accounts, is my site safe?
A: Your risk is lower but not eliminated. Attackers may chain exploits or abuse plugins exposing similar script injection paths. Verify plugin versions and apply updates regardless.

Q: Will WAF rules interfere with WPBakery functionality?
A: Poorly tuned rules can cause false positives. Managed-WP recommends targeted rules blocking only specific malicious patterns, deployed initially in monitoring mode to fine-tune.

Q: How long will remediation take if my site was compromised?
A: Depends on infection scope. Single post cleanup may take minutes; widespread infection requires a thorough forensic approach, sometimes 1-3 days.

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Final Takeaway — Prioritize Timely Updates and Layered Security

This stored XSS vulnerability in WPBakery Page Builder is a timely reminder that permitting raw JavaScript in your content creation workflow without stringent controls can create dangerous attack vectors. Although the patch in version 8.7 remedies the immediate issue, remember:

• Apply updates swiftly.
• Limit the ability to inject scripts to trusted users only.
• Deploy managed WAF services to block exploit attempts proactively.
• Continuously scan and sanitize stored content.
• Enforce least privilege and utilize multi-factor authentication.

If you need expert assistance with rule creation, scanning, or remediation, Managed-WP is here to help. You can start with our free Basic plan for instant protection while you work through the updates and cleanup.

Stay vigilant, and protect your WordPress environment rigorously—custom JavaScript features offer flexibility, but they require careful management.

— Managed-WP Security Team