Critical Advisory: Broken Access Control Vulnerability in “Sliper for Elementor” Plugin (≤ 1.0.10)

Date: December 31, 2025
Author: Managed-WP Security Experts

Managed-WP is alerting WordPress site owners and developers about a significant broken access control vulnerability identified in the “Sliper for Elementor” plugin, versions 1.0.10 and earlier, tracked as CVE-2025-66157. This vulnerability allows authenticated users with minimal privileges (Subscriber role) to perform actions normally restricted to higher-level administrators due to missing or inadequate authorization checks.

As of this advisory, no official patch has been released by the plugin vendor. Managed-WP strongly recommends implementing immediate mitigations such as applying virtual patches via Web Application Firewall (WAF) rules, adjusting server configurations, and utilizing recommended code fixes where possible. This advisory delivers a comprehensive analysis including the technical background, exploitation scenarios, detection strategies, and recommended defense measures serving WordPress professionals committed to maintaining secure sites.

Summary of the Vulnerability

• Affected Plugin: Sliper for Elementor
• Vulnerable Versions: Versions ≤ 1.0.10
• Vulnerability Type: Broken Access Control
• CVE Identifier: CVE-2025-66157
• Required Privilege for Exploitation: Authenticated Subscriber role
• Severity Rating: Low (CVSS 5.4), but impact varies by exposed functionality
• Current Patch Status: No official patch available
• Immediate Risk: Unauthorized privileged operations by low-level users, potentially leading to unauthorized changes or content injection

Understanding Broken Access Control in WordPress Plugins

Broken access control vulnerabilities arise when plugins fail to properly restrict access to sensitive functionality reserved for higher privilege users such as administrators or editors. Effective access control in WordPress depends on:

• Proper use of capability checks (e.g., current_user_can('manage_options'))
• Implementation of nonces to verify intent (check_admin_referer(), check_ajax_referer())
• Secure permission callbacks for REST API endpoints
• Restricting direct access to sensitive plugin files and AJAX actions

Failure to enforce these controls means that a user with minimal permissions (such as a Subscriber) can invoke functions reserved for higher-level users, potentially causing unauthorized modifications or security breaches.

Potential impacts of exploiting broken access control include:

• Changes to plugin settings or content (e.g., slider configurations)
• Injection of malicious content or scripts (stored XSS)
• Unauthorized file uploads, possibly enabling remote code execution
• Data exfiltration or malicious network activity initiated by the site

How Attackers Exploit This Vulnerability

The attack typically proceeds as follows:

1. Attacker gains or registers a Subscriber-level account.
2. Identifies vulnerable plugin endpoints (admin-ajax actions or direct PHP files).
3. Sends crafted POST requests to these endpoints without proper authorization checks.
4. Performs unauthorized privileged actions such as modifying plugin data or uploading files.
5. Leverages changes to persist malicious content or escalate further attacks.

Note: Exploitation requires authenticated access. Remote unauthenticated attacks are not possible solely via this vulnerability.

Real-World Impact and Risk Assessment

While rated “Low” by CVSS, the true risk depends on the plugin’s functional exposure within each site:

• Low to Medium: Unauthorized modification of visuals or slider content causing defacement or misrepresentation.
• Medium: Risk of malicious file uploads, which is higher on permissive server configurations.
• High (Chained Attacks): Potential remote code execution or data leaks if plugin settings permit loading external scripts.

We urge site owners not to underestimate this risk and to implement mitigations proactively.

Indicators of Compromise (IoCs) to Watch For

• Unexpected POST requests to admin-ajax.php with action parameters related to ‘sliper’ plugin
• Increased POST frequency from Subscriber accounts targeting plugin endpoints
• New or suspicious media files or slides with unusual timestamps
• Presence of unusual files in upload directories
• New scheduled plugin tasks or cron jobs added without authorization
• Malware alerts related to plugin folders or content
• Repeated access attempts or scanning activity targeting plugin paths logged by server

Immediate Mitigations for Site Owners

1. Deactivate or Remove the Plugin: The safest immediate measure is to disable the vulnerable plugin if functionality permits.
2. Block Plugin Files at Server Level: Use Apache .htaccess or Nginx rules to deny access to plugin PHP files. Example Apache snippet:

   <FilesMatch "\.(php)$">
     Require all denied
   </FilesMatch>
   

3. Deploy Virtual Patching with WAF: Configure firewall rules to block POST requests to vulnerable plugin endpoints from non-administrator users.
4. Implement AJAX Capability Checks: Add a Must-Use plugin (mu-plugin) to enforce admin privileges on sensitive AJAX actions (example code provided below).
5. Reset Passwords and Enable 2FA: For all privileged users, reset credentials and enforce two-factor authentication to reduce risk of compromised accounts.
6. Monitor Logs and Scan for Malware: Conduct thorough scans and review logs for suspicious activity related to the plugin.
7. Restrict Subscriber Permissions: Ensure Subscriber role only has minimal capabilities.
8. Audit User Accounts: Remove or demote any unknown or suspicious users.
9. Follow Cleanup Procedures if Compromise Detected: Isolate, backup, scan, clean, and restore as needed following incident response protocols.

Sample Defensive Mu-Plugin to Enforce Privilege Check

To minimize risk until an official patch is available, deploy this mu-plugin code. It blocks critical AJAX actions for users without administrator rights. Save as mu-guard-sliper.php inside wp-content/mu-plugins/.

 'Insufficient privileges'), 403);
            }
        }
    }
});
?>

Customize $blocked_actions with all vulnerable AJAX action names relevant to the plugin.

Recommended Permanent Developer Fixes

1. Enforce explicit capability checks on all privileged code paths (e.g., current_user_can('manage_options')).
2. Implement robust nonce verification for admin and AJAX interactions.
3. Ensure REST API endpoints define secure permission_callback functions.
4. Sanitize and escape inputs and outputs rigorously.
5. Prevent direct URL access to plugin PHP files unless properly gated within WordPress context.
6. Strictly validate and restrict any file uploads to safe types and directories.
7. Create automated tests that verify non-admin users cannot invoke privileged actions.

Example snippet for securely handling an AJAX request:

add_action('wp_ajax_sliper_save_settings', 'sliper_save_settings_handler');

function sliper_save_settings_handler() {
    if (!current_user_can('manage_options')) {
        wp_send_json_error(array('message' => 'Unauthorized'), 403);
    }
    check_ajax_referer('sliper_save_nonce', 'security');

    // Process validated input here...
}

Incident Response Guidance for Suspected Exploitation

1. Isolate the site: Take it offline or enable maintenance mode.
2. Create full backups: Capture database and files for forensic purposes.
3. Scan and clean: Use malware detection tools to remove malicious files or code.
4. Verify file integrity: Compare to official plugin and WordPress files, restore as needed.
5. Audit users/roles: Remove unauthorized accounts, reset passwords, and rotate API keys.
6. Rotate security keys and salts: Update wp-config.php to invalidate sessions.
7. Legal compliance: Assess notification obligations if user data was compromised.
8. Apply mitigations: Reinstall patched plugins, apply WAF rules, reinforce configurations.
9. Enhanced monitoring: Maintain heightened vigilance over logs post-incident.

Consider engaging a professional security service for comprehensive incident handling if needed.

Long-Term Security Best Practices

• Adopt the principle of least privilege for user roles and capabilities.
• Avoid augmenting Subscriber role permissions unnecessarily.
• Keep plugin use minimal and regularly audit active plugins.
• Test and review plugin upgrades in staging environments before production deployment.
• Employ managed WAF solutions and keep virtual patching updated.
• Enforce strong password policies and two-factor authentication for all elevated users.
• Automate backups and ensure rapid restoration capabilities.
• Integrate security scanning into development workflows.
• Review third-party plugins by code inspection, not just popularity.

Quick Server-Level Mitigation with Nginx

Administrators managing their own servers can add this Nginx configuration to block direct PHP file execution in the vulnerable plugin directory:

location ~* ^/wp-content/plugins/sliper-elementor/.*\.php$ {
    deny all;
    return 403;
}

Warning: Implementing this block may disrupt plugin functionality if PHP files are required to render front-end content. Use as a temporary measure while applying safer mitigations.

Why Impact May Differ Across Sites

• Sites with many Subscriber accounts (for example, membership or community platforms) face broader attack surface.
• Hosting environments with lenient file upload settings increase risk of exploitation.
• Plugins exposing dynamic content rendering are vulnerable to persistent XSS or defacement.

Site-specific risk analysis is critical—low rated vulnerabilities can be serious depending on context.

Additional Protective Measures Available from Managed-WP

While you prepare or implement mitigations, Managed-WP offers immediate protective solutions:

• WAF-based virtual patching blocks suspicious plugin endpoint access automatically.
• Continuous real-time monitoring and alerting for suspicious activity.
• Expert remediation and detailed security guidance tailored to your site.

Contact Managed-WP support for assistance integrating these defenses.

Essential Immediate Steps for Site Owners

1. Check if “Sliper for Elementor” (≤ 1.0.10) is active on your site.
2. Temporarily deactivate or uninstall the plugin, if possible.
3. If deactivation is not feasible, deploy virtual patches or WAF rules to block vulnerable endpoints.
4. Review server and WordPress logs for suspicious admin-ajax or plugin file access.
5. Run thorough malware scans on files and database.
6. Take incident response actions if signs of breach are detected.
7. Apply long-term best practices including privilege minimization, 2FA, backups, and managed WAF services.

Closing Remarks from Managed-WP Security Experts

This vulnerability is a reminder that rigorous authorization checks are fundamental for WordPress plugin security. Every privileged operation must verify user capability and nore verification tokens (nonces). Managed-WP recommends that site owners adopt comprehensive defenses combining operational best practices with managed security services.

Should you require support implementing virtual patching, incident response, or tailored site hardening, our dedicated security team stands ready to assist. Ensure continuous vigilance, log analysis, and prompt mitigation to keep your WordPress environment safe.

— Managed-WP Security Team

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