Plugin Name	Add Multiple Marker
Type of Vulnerability	Broken Access Control
CVE Number	CVE-2025-11999
Urgency	Low
CVE Publish Date	2025-11-10
Source URL	CVE-2025-11999

Urgent: Add Multiple Marker (≤ 1.2) — Missing Authorization Enables Unauthenticated Settings Changes (CVE-2025-11999)

Date: 11 November 2025
Author: Managed-WP Security Team

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Executive Summary

• Severity: Low (CVSS 5.3)
• Affected Software: Add Multiple Marker WordPress plugin (versions ≤ 1.2)
• Vulnerability Type: Broken Access Control allowing unauthorized settings modification
• Access Required: None (Unauthenticated)
• CVE Identifier: CVE-2025-11999

As US-based security experts at Managed-WP, we provide this technical brief targeted at WordPress site administrators, developers, and security teams. The goal is to quickly understand the risk posed by this vulnerability and implement immediate mitigations to secure your environment.

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Table of Contents

1. Understanding the Vulnerability in Plain English
2. Risk and Impact: Why This Matters to Your Site
3. Technical Root Cause: What Developers Did Wrong
4. How Attackers Exploit This Vulnerability
5. Detecting Signs of Compromise and Conducting Forensics
6. Immediate Steps to Mitigate Risk Before Official Patch
7. Recommended Managed-WP WAF Rules and Virtual Patching
8. Long-Term Secure Development Practices for Plugin Authors
9. Incident Response Guidance for Suspected Exploitation
10. How Managed-WP Assists with Protection and Remediation

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1) Understanding the Vulnerability in Plain English

The Add Multiple Marker plugin up to version 1.2 contains a critical broken access control vulnerability allowing unauthenticated users to update plugin settings. Essentially, the plugin exposes an insecure endpoint or API route that accepts settings changes without confirming the identity or privileges of the requester.

This flaw means that anyone on the internet—even without logging in—can alter plugin configuration. While the vulnerability severity is rated “Low,” the implications vary based on what settings are modified, including redirect URLs, API credentials, enabled features, or injected HTML. Attackers exploit this to facilitate secondary attacks or disrupt site operation.

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2) Risk and Impact: Why This Matters to Your Site

Though scored as low severity, the real-world consequences are often significant depending on plugin usage and configuration. Potential impacts include:

• Persistent Malicious Changes: Attackers could modify redirect targets, insert unauthorized links, or enable insecure options.
• Data Exposure or Misuse: If API keys or service endpoints are stored in settings, these could be compromised and abused.
• Privilege Escalation: Altered settings might trigger further vulnerabilities, such as stored cross-site scripting or admin notification bypasses.
• Brand and SEO Damage: Malicious redirects and hidden content can erode user trust and search engine rankings.
• Mass Exploitation: Since the plugin is used on multiple sites, automated attacks can modify configurations at scale.

Because no authentication is required, this vulnerability invites automated scanning and opportunistic exploitation.

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3) Technical Root Cause: What Developers Did Wrong

The vulnerability arises primarily due to the plugin’s failure to enforce proper authorization controls on settings update operations. Common mistakes in the plugin’s code include:

• Missing or insufficient capability checks before updating options (update_option calls without verifying current_user_can('manage_options')).
• Absence of nonce verification to confirm requests originate from legitimate user actions.
• Exposing action handlers via admin-ajax.php or REST API endpoints without authentication or adequate permission callbacks.
• Accepting and storing unsanitized input, enabling secondary injection issues.
• Confusing authentication with authorization, thereby trusting requests solely based on their origin or structure.

Plugins must implement both authentication and strict authorization checks to protect privileged actions such as settings modifications.

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4) How Attackers Exploit This Vulnerability

An attacker probes the site for exposed endpoints that allow settings changes without login. Once identified, they craft HTTP requests carrying arbitrary settings data and send these against the vulnerable plugin’s endpoints. The plugin accepts and persists these values, enabling the attacker to manipulate site behavior, redirects, or confidential keys.

We refrain from publishing exploit payloads to prevent misuse. Instead, this overview guides defenders in recognizing and mitigating the attack surface.

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5) Detecting Signs of Compromise and Conducting Forensics

Configuration Checks

• Review the plugin’s settings page in WordPress admin for unexpected or suspicious values.
• Examine wp_options (or equivalent options table) for unusual recent modifications linked to the plugin.
• Search the database for suspicious strings like unfamiliar domains, encoded data, or scripts.

Log Analysis

• Review web server access logs for repeated or anomalous POST requests to admin-ajax.php, admin-post.php, or plugin endpoints from unfamiliar IP addresses.
• Look for unusual parameter patterns or traffic at odd times.

File and Content Integrity

• Scan for unexpectedly changed theme/plugin files or timestamps inconsistent with routine updates.
• Verify no unauthorized admin user accounts have been created.
• Search content and metadata for injected links or scripts.

Application Logging

• Check audit logs for unauthorized settings updates or database writes.

Backup Comparison

• Compare current option values and files with recent backups to identify changes.

If any indicators of compromise are found, immediately escalate to appropriate incident handling.

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6) Immediate Steps to Mitigate Risk Before Official Patch

1. Disable or Remove the Plugin if Not Essential
   • Deactivating unnecessary plugins is the most effective immediate mitigation.
2. Restrict Access to Plugin Endpoints Via Web Server Rules
   • Use .htaccess or Nginx rules to limit access to sensitive plugin PHP files or AJAX endpoints to trusted IPs or authenticated users.
3. Protect the Admin Area
   • Implement HTTP Basic Authentication or IP whitelisting on wp-admin to reduce unauthorized access risks.
4. Deploy Web Application Firewall (WAF) Rules or Virtual Patches
   • Block or rate-limit unauthenticated POST requests targeting the plugin’s settings update actions.
5. Monitor for Suspicious Activity and Issue Alerts
   • Set up notifications on unexpected changes to plugin configuration or unusual admin endpoint POST traffic.
6. Rotate Any Potentially Exposed API Keys or Secrets
   • Change tokens stored within the plugin immediately if exposed.
7. Take a Full Backup and Isolate It
   • Create comprehensive backups of files and database for forensics and recovery.
8. Notify Relevant Stakeholders
   • Communicate risk and mitigation plans to team members or clients when appropriate.

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7) Recommended Managed-WP WAF Rules and Virtual Patching

For hosting providers, security teams, and site owners utilizing Managed-WP, virtual patching is an essential rapid response to zero-day vulnerabilities.

High-Level Rule Recommendations:

• Block unauthenticated POST requests aimed at modifying plugin-specific options or including suspicious parameters.
• Rate-limit or block POST traffic to admin-ajax.php or admin-post.php with action parameters matching the vulnerable plugin.
• Enforce valid WordPress-origin headers and nonce verification for state-changing requests where feasible.
• Filter requests containing common attack payload markers (e.g., embedded script tags, encoded data).
• Deploy geo-restrictions or reputation-based blocking if your site is under targeted attack.
• Alert on unusual option update attempts for human review.

Operational Considerations:

• Start with detection-only mode to tune rule accuracy, then enable full block mode once confident.
• Deploy multilayered defenses: at CDN, WAF, and origin server levels.
• Customize rules to minimize false positives and avoid disrupting normal site functions.

Managed-WP’s Approach:

• Proactive, targeted blocking of unauthenticated settings update requests.
• Low false-positive virtual patches tailored specifically for this and similar vulnerabilities.
• Concierge onboarding and managed escalation for affected customers until official patches are released.

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8) Long-Term Secure Development Practices for Plugin Authors

Plugin developers must rigorously enforce authentication and authorization for all actions that modify site state. Recommended code practices include:

• Always check user capabilities (e.g., current_user_can('manage_options')) before updating plugin settings.
• Implement server-side nonce verification using check_admin_referer or wp_verify_nonce for all state-changing requests initiated via admin UI.
• Define REST API routes with explicit and secure permission_callback functions instead of allowing open access.
• Restrict admin-ajax.php actions to authenticated users for privileged operations; use check_ajax_referer as appropriate.
• Sanitize all inputs thoroughly before storing or processing using functions like sanitize_text_field, esc_url_raw, and wp_kses_post.
• Avoid storing sensitive credentials as plain text; implement proper access controls.
• Maintain audit logging for configuration changes, including actor identity and request origin.
• Use safe default values and validate inputs to prevent malformed or harmful configurations.
• Incorporate automated tests to verify unauthorized users cannot update settings.

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9) Incident Response Guidance for Suspected Exploitation

1. Isolate the Site
   • Enable maintenance mode or restrict access to minimize ongoing damage.
2. Snapshot and Backup Everything
   • Document current state via comprehensive backups of files, database, and logs before making changes.
3. Rotate Credentials
   • Reset all admin passwords, API keys, and plugin token credentials.
4. Remove or Harden Vulnerable Plugin
   • Deactivate and delete the plugin if possible; otherwise, apply virtual patches and access controls.
5. Clean and Restore
   • Restore from a known clean backup if available.
   • If cleaning in place, remove rogue users, malicious files, and injected content carefully.
6. Conduct Thorough Scans
   • Run malware scans and check cron jobs, plugins, and themes for suspicious changes.
7. Notify Your Hosting Provider and Stakeholders
   • Engage providers for deeper forensic support and comply with any relevant disclosure requirements.
8. Implement Monitoring and Ongoing Security Measures
   • Deploy WAF, schedule regular backups, and improve logging and auditing.

If unsure, consult professional WordPress incident response experts immediately.

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10) How Managed-WP Assists with Protection and Remediation

Immediate Protection with Managed-WP Basic (Free)

Automated scanners and attackers move fast after vulnerabilities are disclosed. Managed-WP offers a free protection tier providing essential mitigations that help block exploitation attempts swiftly:

• Managed Web Application Firewall (WAF)
• Unlimited bandwidth protection
• Automated malware scanning
• Mitigation of OWASP Top 10 risks

For enhanced protection and remediation:

• Standard Plan — $50/year: Adds automatic malware removal and IP blacklist/whitelist management.
• Pro Plan — $299/year: Includes virtual patching for vulnerabilities, monthly reporting, premium support, and expert services.

Sign up for immediate protection here: https://managed-wp.com/pricing

Managed-WP applies targeted virtual patches for critical vulnerabilities like CVE-2025-11999 to help prevent exploitation even before plugin patches become available.

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Practical Action Checklist for Site Owners

1. Identify Sites Running Add Multiple Marker ≤ 1.2
2. Deactivate and Remove the Plugin if Not Required
3. Restrict Access to Plugin Endpoints and Admin Areas
4. Backup All Files, Databases, and Logs
5. Monitor for Unusual Activity on Plugin Options
6. Enforce Strong Admin Passwords and Two-Factor Authentication
7. Disable In-WordPress File Editors (define('DISALLOW_FILE_EDIT', true);)
8. Deploy Targeted WAF Rules to Block Unauthorized Settings Changes
9. Rotate API Keys or Secrets Stored by the Plugin
10. Engage Hosting Provider or Incident Response Professionals as Needed

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For Hosting Providers and Managed WordPress Platforms

This vulnerability is a prime candidate for rapid, preventive virtual patch deployment across customer environments:

• Identify customers with vulnerable plugin versions and communicate remediation steps clearly.
• Apply HTTP-layer blocking for unauthenticated requests targeting plugin settings endpoints.
• Offer opt-in automatic protection until vendor patches are available.
• Maintain transparent communication and incident tracking for affected clients.

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For Developers and Security Auditors

When reviewing WordPress plugins, focus on potential security gaps like this broken access control vulnerability by paying close attention to:

• All calls to functions modifying persistent data (update_option, delete_option, etc.) and their authentication/authorization context.
• admin-ajax.php actions and REST API route registrations for proper permission callbacks.
• Writing and running tests simulating unauthorized access attempts to privileged endpoints.

Perform code base searches for update_option and validate each path includes strict user capability checks and nonce validations.

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Closing Thoughts

Broken access controls remain a leading cause of critical WordPress plugin vulnerabilities. Even seemingly minor issues such as unauthenticated settings updates can enable attackers to establish footholds or chain attacks into full site compromises.

Site owners should adopt a proactive security posture:

• Maintain current inventories of all installed plugins and versions.
• Apply rigorous access controls and enforce least privilege on admin areas.
• Deploy managed WAF and virtual patching services to guard against emerging threats.
• Perform regular audits and maintain close communication with your hosting or security partners.

Managed-WP’s Basic (Free) plan provides immediate critical protection layers including WAF, malware scanning, and automated virtual patches to help you maintain security during vulnerability disclosure and remediation periods. Start protecting your site now: https://managed-wp.com/pricing

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Appendix: Additional Resources

• CVE-2025-11999 Reference: Official CVE entry and searchable databases.
• WordPress Hardening Guide: Follow WordPress.org’s official security hardening best practices.
• Developer Security Checklist: Include capability checks, nonce verification, input sanitization, and permission callbacks.

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If you require assistance, Managed-WP can provide:

• Vulnerability audit templates tailored to your site inventory.
• Custom WAF rule sets to block plugin-specific vulnerability vectors.
• Guidance to tighten wp-admin access for specific environments.

Contact Managed-WP support or subscribe to our protection plans for seamless, expert-managed defenses.

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