Urgent Security Advisory: YourMembership Single Sign On Plugin (<= 1.1.7) – Unauthenticated Access Leak (CVE-2025-10648)

Published: October 15, 2025
作者： Managed-WP Security Team

This advisory is issued by Managed-WP, a leading WordPress security specialist based in the United States. Our intent is to clearly outline the risks associated with this vulnerability, illustrate potential attacker behaviors, and provide immediate, actionable mitigation tactics for WordPress administrators and security professionals.

Executive Summary

A broken access control vulnerability identified as CVE-2025-10648 affects versions 1.1.7 and earlier of the “Login with YourMembership – YM SSO Login” WordPress plugin. The flaw originates from an exposed function intended for internal use, which leaks sensitive test attributes without verifying authorization credentials. This oversight allows any unauthenticated actor to query and retrieve restricted information that should remain confidential.

While the CVSS rating for this issue is classified as moderate (5.3), the operational context elevates its importance—since exposed data can reveal critical identifiers, configuration details, and debug information. Such intelligence can be weaponized to mount follow-up attacks such as credential stuffing, targeted phishing, and privilege escalation. As of this publication date, no official patch is available from the plugin developer.

If your infrastructure includes this plugin, prioritize immediate evaluation and enforcement of mitigative controls. Recommended protective measures include disabling the plugin, instituting access restrictions via Web Application Firewalls (WAFs), or isolating the vulnerable endpoint pending official remediation.

Understanding the Vulnerability

• 類型： Broken Access Control / Missing Authorization (OWASP A05)
• Affected Functionality: moym_display_test_attributes method within the plugin
• Affected Versions: YM SSO Login plugin up to and including 1.1.7
• Access Required: None (unauthenticated)
• 參考： CVE-2025-10648

This vulnerability occurs because the plugin exposes an internal diagnostic function without performing any authentication or authorization checks. An attacker can invoke this function remotely and receive internal “test attributes” that should be strictly protected.

Based on typical disclosures of this nature, the leaked information may include but is not limited to:

• Debug flags and internal tokens
• User/member identifiers
• Configuration parameters and internal API endpoints
• Partial Single Sign-On (SSO) mappings
• Error outputs that may disclose server environment details

Even seemingly trivial exposed data can significantly reduce the attacker’s effort by providing reconnaissance information and facilitating targeted attacks.

Why This is Critical: The Practical Impact

1. Reconnaissance Enabler: Attackers gain insights into your SSO setup, including identifiers and configuration data, which aid in crafting more precise and effective attacks such as credential stuffing and social engineering.
2. Potential Credential Exposure: Though full credentials are not confirmed present, debug outputs sometimes include partial tokens or API keys, which could be leveraged in attacks.
3. Privilege Escalation Risks: Understanding SSO mappings allows attackers to design impersonation or elevation schemes, increasing the threat scope.
4. Vulnerability Chaining: This flaw may serve as an entry point for further exploitation when combined with other weaknesses.
5. Automated Mass Exploitation: Absence of authentication enables widespread automated scanning and exploitation campaigns.

Due to these factors, it is imperative to remediate this vulnerability swiftly despite its “low” urgency label.

Potential Attacker Methods

While we do not provide exploit code, the conceptual exploitation process may include:

1. Locating the vulnerable plugin endpoint via automated vulnerability scanners or by probing common WordPress AJAX and plugin-specific REST endpoints.
2. Invoking the moym_display_test_attributes action without authentication credentials.
3. Harvesting returned data to identify API endpoints, debug flags, or user identifiers.
4. Leveraging gathered intel for advanced attacks such as targeted phishing, token generation attempts, or chaining with other vulnerabilities.

The availability of unauthenticated access makes this vulnerability highly attractive for large-scale scanning and exploitation.

How to Identify If Your Site Is Impacted

1. Plugin Inventory: Scan all WordPress environments for the presence of “Login with YourMembership – YM SSO Login” plugin version 1.1.7 or older.
2. Log Review: Check access and application logs for suspicious requests to:
   • admin-ajax.php?action=moym_display_test_attributes
   • URLs containing /login-with-yourmembership/ plugin paths
   • Requests returning unauthorized internal data containing keywords like “test” or “moym”
3. Security Scanning: Use trusted WordPress vulnerability scanners or security services to detect the vulnerable plugin version and missing authorization.
4. Code Inspection (if qualified): Review plugin source for the moym_display_test_attributes function, verifying if proper user capability checks (current_user_can('manage_options')) or nonces are used. Lack of such checks confirms vulnerability.

重要的： Limit testing to systems under your ownership or explicit permission to avoid unauthorized scanning.

Immediate Mitigations You Can Apply

1. Disable or Remove the Plugin: If the feature is not critical, deactivate and uninstall the YM SSO Login plugin to eliminate the exposure.
2. WAF or Server-Level Access Restrictions: Block requests targeting the vulnerable action, for example:
   • Deny requests to admin-ajax.php 和 action=moym_display_test_attributes
   • Restrict access to plugin PHP files via web server rules
3. Enforce Authentication at the Server Level: Protect plugin endpoints with .htaccess or nginx-authentication rules to prevent unauthenticated access.
4. IP-Based Access Controls: Limit access to plugin endpoints only to trusted IP addresses if possible.
5. Temporary Code Alterations: Rename or comment out the vulnerable function with careful testing and backups (recommended only for administrators with development expertise).
6. Disable Debugging and Error Output: Ensure WP_DEBUG and error display are off in production to reduce information leakage.
7. Monitor Logs and Set Alerts: Increase logging and create alerts for unexpected access patterns, particularly unauthenticated 200 HTTP responses involving the plugin endpoints.

Sample Virtual Patching / WAF Rules (Conceptual)

Below are example defensive controls for your Web Application Firewall. Adapt them to your platform’s syntax (ModSecurity, nginx, Cloud WAF, etc.):

• Block requests to admin-ajax.php where query parameter equals action=moym_display_test_attributes and requests are unauthenticated.
• Deny access to plugin files paths containing /wp-content/plugins/login-with-yourmembership/ if suspicious parameters like moym 或者 display_test_attributes are present.
• Rate-limit or present CAPTCHA challenges for unauthenticated requests targeting known vulnerable plugin endpoints.
• Restrict REST API endpoints exposed by this plugin by requiring authentication or complete block until patched.

Example Concept: If path includes admin-ajax.php, query includes action=moym_display_test_attributes, and user is unauthenticated, then return HTTP 403 Forbidden or a CAPTCHA challenge.

Long-Term Remediation and Best Practices

1. 外掛程式管理： Remove unused plugins and keep critical ones updated using test environments before production deployment.
2. SSO Security Hardening: Treat SSO connectors as sensitive infrastructure requiring least privilege and careful privilege mapping.
3. Disable Testing Endpoints in Production: Ensure that any test/debug features are disabled in live environments.
4. Defense in Depth: Layer protections including WAF, host/network access controls, two-factor authentication, and IP whitelisting of admin areas.
5. Incident Preparedness: Maintain documented incident response plans, perform regular backups, and ensure recovery processes are tested.
6. Logging and Monitoring: Centralize log management and set up alerts for anomalous plugin endpoint accesses or unexpected administrative activity.

If You Suspect Exploitation – Immediate Actions

1. Isolate the Site: Engage maintenance mode or isolate network connectivity if possible to prevent further damage.
2. Preserve Logs: Secure all relevant logs for forensic analysis, including web, application, and plugin logs.
3. Rotate Credentials: Update API keys, SSO secrets, and administrative passwords in a coordinated manner.
4. Conduct Full Security Scans: Use trusted security tools or engage professionals to detect malware or backdoors.
5. Clean/Rebuild: Restore from a known good backup if compromise is confirmed and conduct post-cleanup hardening.
6. Perform Root Cause Analysis: Identify and close the vulnerability vector, documenting lessons learned.

Monitoring and Detection Recommendations

• Set alerting for any unauthenticated HTTP 200 responses containing substrings like “moym” or “test_attributes”.
• Monitor repeated failed login attempts following suspected reconnaissance activities.
• If utilizing SIEM platforms, correlate plugin endpoint access with subsequent successful logins from the same IP within a 48-hour window for high-priority alerts.

Why Virtual Patching is Critical

Until official patches are issued by plugin vendors, virtual patching through a WAF is your fastest defense. It intercepts malicious traffic targeting the vulnerability before it reaches the plugin code, significantly reducing the exposure window and buying time for thorough patch deployment and testing.

Managed-WP’s approach emphasizes narrow, precise WAF rules to prevent false positives while thwarting mass exploitation attempts.

Communication Guidance for Managed WordPress Environments

For Managed-WP administrators or service providers supporting clients, clear communication is essential:

• Notify site owners about the vulnerability impacting YM SSO Login versions 1.1.7 and earlier with immediate mitigation recommendations.
• Outline your remediation plan, including plugin audits, enforcement of access controls, monitoring, and update coordination.
• If managing SSO integrations, collaborate with identity providers to consider rotating client secrets and reviewing trust boundaries.

Transparent and timely messaging reduces uncertainty and promotes adherence to security best practices.

Example Server-Level Quick Fixes

Consider deploying these server configurations with appropriate staging validation:

• Apache (.htaccess): Deny direct access to specific vulnerable plugin PHP files by returning HTTP 403.
• nginx: Return HTTP 403 responses for any admin-ajax.php requests containing action=moym_display_test_attributes.

These controls should be narrowly scoped to prevent unintended service disruptions, ideally applying only to unauthenticated clients.

Administrator Checklist

1. Identify all WordPress installations running the vulnerable plugin and note versions.
2. If found running ≤1.1.7, execute at least one of the following immediately:
   • Deactivate and remove the plugin if not essential.
   • Apply WAF rules blocking vulnerable plugin actions.
   • Restrict plugin files with strict server access controls or IP whitelisting.
3. Audit logs for suspected exploit attempts over recent months.
4. Rotate secrets for SSO client integrations if applicable.
5. Plan for patching or plugin replacement once updates become available.
6. Enhance monitoring for related abnormal access or administrative activity.
7. Document all actions and communicate to relevant stakeholders promptly.

How Managed-WP Enhances Security

Managed-WP offers comprehensive services to defend against vulnerabilities like CVE-2025-10648, including:

• Tailored WAF signatures designed to precisely block unauthorized calls to vulnerable functions without impacting legitimate traffic.
• Automated scanning to identify vulnerable plugin instances across client environments.
• Proactive monitoring and alerting systems detecting attack reconnaissance and subsequent malicious activity.
• Assistance with emergency mitigation, including virtual patching and plugin code reviews.
• Post-incident cleanup guidance and validation to ensure restored system integrity.

For organizations managing multiple WordPress sites or client portfolios, these capabilities provide peace of mind and reduce exposure latency until official plugin patches are released.

Final Recommendations and Responsible Disclosure

• Treat this vulnerability as an immediate security concern due to unauthenticated access to internal plugin attributes.
• Plugin developers or security researchers with further actionable technical details should coordinate disclosure responsibly with plugin vendors and security entities.
• Public exploit code should be withheld from general distribution to avoid enabling widescale attacks.

Managed-WP stands ready to assist with virtual patching, security rule creation, and comprehensive site audits to protect your WordPress installations until official patches are available.

Security is a continuous commitment. Prioritize securing your SSO integration as a critical element of your WordPress environment.

— Managed-WP Security Team