Authenticated Contributor Stored XSS in ONLYOFFICE DocSpace (<= 2.1.1) — Critical Guidance for Site Owners

Executive Summary: A stored Cross-Site Scripting vulnerability identified as CVE-2024-11750 impacts ONLYOFFICE DocSpace plugin versions 2.1.1 and earlier. This flaw allows users with Contributor privileges to embed persistent malicious scripts that execute when other users access affected pages. The vulnerability has been patched in version 2.1.2. This detailed briefing provides a clear assessment of the threat, attack vectors, detection techniques, and immediate practical mitigation strategies — including managed Web Application Firewall (WAF) protection and recommended configuration actions if immediate updates are not feasible.

Table of contents

• Incident Overview
• Technical Breakdown of the Vulnerability
• Potential Attack Scenarios and Associated Risks
• Affected Versions and Key CVE Information
• Urgent Remediation Steps for Administrators
• Detection Methods for Possible Exploitation
• Temporary Mitigations for Delayed Patching
• Long-Term Security Best Practices
• Immediate Protection via Managed-WP’s Managed WAF
• Appendix: Commands and Code for Incident Response

Incident Overview

On February 3, 2026, security researchers publicly disclosed a stored XSS vulnerability within the ONLYOFFICE DocSpace plugin (CVE-2024-11750). This flaw permits authenticated users with Contributor privileges to inject malicious scripts into document metadata fields, which are then rendered unescaped, causing those scripts to execute in the browsers of users who view the content. Given that Contributors generally cannot publish content, the threat hinges on the eventual viewing of malicious inputs by higher-privileged users such as site administrators. The plugin vendor addressed the vulnerability in version 2.1.2.

This analysis targets WordPress site owners, administrators, and security professionals requiring a rigorous and pragmatic approach to mitigation, detection, and recovery.

Technical Breakdown of the Vulnerability

Stored XSS vulnerabilities occur when malicious input is saved server-side and later rendered unsanitized, allowing arbitrary scripts to run in the context of other users.

Critical technical details for this issue include:

• Required privileges: Contributor role (can create content but lacks publishing rights).
• Vulnerability type: Persistent Stored Cross-Site Scripting.
• Exploitation vector: A Contributor inserts malicious JavaScript into inputs such as document titles, descriptions, or metadata.
• Risk: When a higher-privileged user (editor or admin) accesses the affected content, the script executes with elevated permissions, potentially enabling session theft, privilege escalation, or site compromise.
• Resolution: Updating to ONLYOFFICE DocSpace version 2.1.2 enforces proper sanitization and encoding to neutralize payloads.

This vulnerability is particularly concerning for multi-author environments, educational platforms, and intranet portals where Contributors have submission access.

Potential Attack Scenarios and Associated Risks

The real-world consequences can include:

• Administrator Account Takeover: An injected script steals admin session cookies or tokens, enabling attackers to gain full control over the site.
• Content Defacement and Reputation Damage: Malicious scripts modify page content or inject misleading material, harming brand trust.
• Cross-Site Request Forgery (CSRF) Chaining: Scripts perform unauthorized admin actions by chaining stored XSS with CSRF vulnerabilities.
• Supply Chain Breaches: Scripts exfiltrate sensitive data like internal document IDs or API credentials visible in the admin interface.

Since stored XSS payloads persist, attackers can maintain prolonged access and leverage dormant scripts repeatedly, escalating damage.

Affected Versions and Key CVE Information

• Affected Versions: ONLYOFFICE DocSpace plugin version 2.1.1 and below.
• Patched Version: 2.1.2
• CVE Reference: CVE-2024-11750
• CVSS v3.1 Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L

Despite the “Low” urgency label by some triage systems, the actual exploitation risk varies by site configuration and user roles, and this issue must be managed carefully.

Urgent Remediation Steps for Administrators

1. Immediately update ONLYOFFICE DocSpace to version 2.1.2.
   • Test updates in a staging environment before production rollout to avoid conflicts.
2. Where immediate update is impossible, implement interim mitigations:
   • Disable or suspend Contributor accounts that cannot be validated.
   • Temporarily reduce Contributor permissions or convert affected users to lower privilege roles.
   • Activate content moderation workflows requiring review before Contributor submissions go live.
3. Deploy Managed-WP’s Managed WAF or equivalent virtual patching:
   • Block requests containing typical XSS payloads such as <script> tags or event handler attributes.
   • Protect critical plugin endpoints from exploitation attempts.
4. Scan your site for injected scripts and suspicious content.
5. Rotate administrative passwords and invalidate active sessions if compromise is suspected.
6. Audit logs for unexpected high-privilege actions or user creations.

Detection Methods for Possible Exploitation

An effective response employs a combination of automated and manual inspection:

1. Database queries for suspicious script tags in posts, metadata, and comments.
2. Scanning for encoded or obfuscated scripts including event handlers (e.g., onerror=, onload=).
3. Manual review of recently submitted Contributor content, focusing on document descriptors and metadata.
4. Examination of HTTP logs for anomalies or POST requests containing script-like payloads.
5. Deployment of specialized WordPress security scanners capable of detecting stored XSS.

Temporary Mitigations for Delayed Patching

1. Virtual patching rules via managed WAF:
   • Block or sanitize incoming POST and PUT requests targeting ONLYOFFICE DocSpace endpoints that contain malicious script indicators.
   • Examples: Detect case-insensitive <script\b tags, JavaScript pseudo-protocols, and common event handler attributes.
2. Restrict unfiltered HTML capabilities for Contributor roles:

   <?php
   add_action('init', function() {
       $role = get_role('contributor');
       if ($role && $role->has_cap('unfiltered_html')) {
           $role->remove_cap('unfiltered_html');
       }
   }, 11);
   ?>
   

3. Enforce editorial approval workflows for plugin-submitted content.
4. Temporarily remove or reduce Contributor access as necessary.
5. Sanitize inputs at save time with temporary filters if plugin hooks are available.

Long-Term Security Best Practices

1. Enforce the principle of least privilege for all user roles.
2. Mandate strict input validation, sanitization, and output encoding across plugins.
3. Implement robust nonce and capability verifications on all AJAX and REST API endpoints.
4. Use proper escaping functions such as esc_html() and esc_attr() consistently.
5. Adopt rigorous content moderation workflows for user-generated content.
6. Maintain up-to-date plugins with vulnerability monitoring and responsive patching.
7. Enhance admin access security with two-factor authentication and IP whitelisting.
8. Establish comprehensive logging, alerting, and forensic capabilities.

Immediate Protection via Managed-WP’s Managed WAF

Managed-WP offers an industry-leading managed Web Application Firewall that provides immediate virtual patching tailored to WordPress environments. Highlights include:

• Real-time blocking of known exploit patterns including stored XSS payloads targeting plugins.
• Contextual detection focused on vulnerable plugin endpoints and user roles.
• Automatic content sanitization to prevent injection of malicious scripts.
• Comprehensive logging and forensics for incident analysis.
• Automatic updates of security rules as new vulnerabilities emerge.

For sites servicing multiple users or complex workflows, managed WAF combined with scheduled patch management delivers the best risk reduction.

Appendix: Commands and Code for Incident Response

Ensure you backup your site before executing queries or code changes.

1. Search for script tags in the database via WP-CLI:

   # Posts content
   wp db query "SELECT ID, post_title, post_type FROM wp_posts WHERE post_content LIKE '%<script%' LIMIT 200;"
   
   # Post metadata
   wp db query "SELECT meta_id, post_id, meta_key FROM wp_postmeta WHERE meta_value LIKE '%<script%' LIMIT 200;"
   
   # Comments
   wp db query "SELECT comment_ID, comment_post_ID FROM wp_comments WHERE comment_content LIKE '%<script%' LIMIT 200;"
   

2. Sanitize meta fields to remove scripts (example):

   <?php
   global $wpdb;
   $meta_key = 'onlyoffice_doc_description'; // Verify actual key name
   $rows = $wpdb->get_results( $wpdb->prepare(
       "SELECT meta_id, meta_value FROM {$wpdb->postmeta} WHERE meta_key = %s",
       $meta_key
   ) );
   foreach ( $rows as $row ) {
       $clean = wp_kses( $row->meta_value, array() ); // Strip all HTML
       $wpdb->update( $wpdb->postmeta, array( 'meta_value' => $clean ), array( 'meta_id' => $row->meta_id ) );
   }
   ?>
   

3. Temporary sanitization on save:

   <?php
   add_action( 'save_post', function( $post_id ) {
       if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;
       if ( isset( $_POST['onlyoffice_description'] ) ) {
           $desc = wp_kses( wp_unslash( $_POST['onlyoffice_description'] ), array() );
           update_post_meta( $post_id, 'onlyoffice_description', $desc );
       }
   }, 20, 1 );
   ?>
   

4. Example ModSecurity generic WAF rule (customize per environment):

   SecRule REQUEST_BODY "(?i)(<\s*script\b|javascript:|on(error|load|click|submit)\s*=)" \
       "phase:2,deny,id:1000101,log,msg:'Blocked possible stored XSS payload in plugin input',severity:2"
   

Recommended Incident Response Timeline

1. Within 24 hours:
   • Apply plugin update to 2.1.2 where possible.
   • If update cannot be applied immediately, deploy managed WAF protections and restrict Contributor privileges.
2. Within 72 hours:
   • Perform site-wide scans for injected scripts in posts and metadata.
   • Remove detected malicious content and rotate administrative credentials if indicators of compromise are found.
3. Within 30 days:
   • Implement role hardening and editorial review workflows.
   • Introduce continuous vulnerability monitoring and auto-updates if feasible.

Stored XSS remains one of the most insidious vulnerabilities due to its persistence and potential for severe impact. The definitive solution requires patching the plugin, but thorough layered defenses are essential for minimizing risk during mitigation windows.

Managed-WP is committed to empowering you with the tools, expertise, and rapid virtual patching necessary to defend your WordPress environment effectively.

If you need a tailored checklist or assistance crafting WAF rules suited to your hosting environment (Apache, Nginx, or cloud-based WAFs), please contact Managed-WP support with your hosting details.

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