Executive summary

A broken access control vulnerability (CVE-2025-10648) has been disclosed in the “Login with YourMembership – YM SSO Login” WordPress plugin (versions up to and including 1.1.7). A function that exposes “test attributes” does not enforce authorization. An unauthenticated attacker can trigger this function and retrieve internal information that should not be public.

Although the reported CVSS score is moderate (5.3), exposed data — such as internal identifiers, SSO attributes, debug configuration or endpoints — can be valuable reconnaissance for follow‑on attacks (credential stuffing, SSO abuse, targeted phishing, or privilege escalation). At time of publication no official patch has been released.

If you run sites using this plugin, investigate and mitigate immediately. The safest immediate measures are: deactivate the plugin, block the vulnerable endpoint at the server or gateway, or otherwise restrict access until an official fix is available.

What is the vulnerability?

• Vulnerability type: Broken Access Control / Missing Authorization (OWASP A05)
• Affected component: function/action named moym_display_test_attributes
• Affected versions: YM SSO Login plugin ≤ 1.1.7
• Required privilege: Unauthenticated
• Public identifier: CVE-2025-10648

In short: the plugin exposes internal “test attributes” without performing authorization checks. Any unauthenticated visitor (or automated scanner) can request and receive those attributes.

Typical contents of such “test attributes” in similar disclosures include:

• Internal or debug tokens and flags
• Member or user identifiers
• Internal endpoints or configuration values
• Partial SSO mapping data
• Error messages or stack traces that leak environment details

Even seemingly non-sensitive fields are valuable for attackers performing reconnaissance.

Why this matters — practical impact

1. Reconnaissance and targeted attacks
   Exposed attributes reveal SSO configuration, identifiers and endpoints that make credential stuffing, brute force and social engineering more effective.
2. Credential or token exposure (possible)
   Debug outputs occasionally include API keys or partial tokens that can be abused when combined with other information.
3. Privilege escalation and account mapping
   SSO integration details help attackers map external identities to local roles and craft impersonation attempts.
4. Chainable vulnerability risk
   This issue can be combined with other weaknesses to produce a larger compromise.
5. Mass automated discovery
   Because the endpoint is callable without authentication, automated scanners can enumerate vulnerable sites at scale.

Even with a modest CVSS rating, SSO-related information disclosure should be treated as a high-priority operational security issue.

How attackers might abuse this (high level)

I will not provide exploit code or step‑by‑step instructions. Conceptually, an attacker could:

1. Discover the vulnerable endpoint or action through automated scans or probing common WordPress endpoints (admin-ajax.php, plugin-specific URLs).
2. Invoke the action associated with moym_display_test_attributes without credentials.
3. Parse the returned data for attribute names, debug flags, API endpoints, or identifiers.
4. Use that intelligence for follow-up activity: craft SSO-mapping attacks, targeted phishing, credential stuffing, or combine with other vulnerabilities.

Automated tooling makes the discovery stage trivial at scale.

Detection — how you can check if you’re affected

1. Inventory plugins
   Check all WordPress sites for “Login with YourMembership” / YM SSO Login. If installed and version ≤ 1.1.7, the site is likely vulnerable.
2. Log inspection
   Review webserver and WordPress logs for requests such as:
   • admin-ajax.php?action=moym_display_test_attributes
   • Requests to paths containing /login-with-yourmembership/ or the plugin slug
   • Any request that returns JSON or bodies containing the substring test or moym

   Look for strange user agents, repeated attempts from the same IP, or unauthenticated requests receiving HTTP 200 with unexpected content.

3. Application scanning
   Run a trusted scanner or security audit to identify the vulnerable plugin and missing authorization.
4. Manual code check (read-only)
   If you have access and knowledge, inspect plugin source for a function named moym_display_test_attributes and confirm whether it enforces capability checks (e.g., current_user_can('manage_options')) or nonces. Absence of such checks indicates vulnerability.

Only scan or test sites you own or have permission to test.

Immediate mitigations (apply now)

If you cannot immediately remove or update the plugin, apply one or more of these mitigations:

1. Deactivate and remove the plugin
   If the YM SSO Login plugin is non-essential, deactivate and delete it to remove the attack surface.
2. Restrict access to the plugin endpoints
   Implement server- or gateway-level rules to block requests that invoke the vulnerable action:
   • Block admin-ajax.php requests with action=moym_display_test_attributes.
   • Block requests to plugin file paths (e.g., any path containing /wp-content/plugins/login-with-yourmembership/ when accompanied by related parameters).

   Use your web application gateway, reverse proxy, or server configuration to enforce these blocks.

3. Add authentication at the server level
   Use basic auth, .htaccess rules, or equivalent nginx protections to prevent unauthenticated access to plugin PHP files until a patch is available.
4. Limit access by IP
   If only internal staff need the functionality, restrict access to known IP ranges via firewall or server rules.
5. Temporarily disable or remove the vulnerable function
   If you can safely edit plugin code and have deployment/testing capability, comment out or rename the function that outputs test attributes. Always back up and test in staging first.
6. Disable debug output
   Ensure WP_DEBUG is false in production and disable display_errors so stack traces and debug data are not exposed.
7. Increase monitoring
   Raise logging and alerts for unauthenticated 200 responses on plugin endpoints, and monitor for suspicious login patterns.

Suggested WAF / virtual patching rules (examples)

Below are defensive concepts. Adapt to your gateway or server syntax (mod_security, nginx, Cloud WAF, etc.). These examples are intentionally generic:

• Block query parameter action=moym_display_test_attributes in requests to admin-ajax.php for unauthenticated sessions.
• Block requests to paths containing /wp-content/plugins/login-with-yourmembership/ that include GET/POST parameters like moym or display_test_attributes.
• Rate-limit or challenge unauthenticated requests targeting plugin endpoints (CAPTCHA or challenge-response).
• For REST endpoints exposed by the plugin, require authentication or deny the endpoint until patched.

Conceptual pseudo-rule:

If request path contains "admin-ajax.php" AND query contains "action=moym_display_test_attributes" AND user is unauthenticated => return 403 or present a challenge.

Keep rules narrow to avoid blocking legitimate admin traffic (e.g., only block unauthenticated requests, or only block specific query parameters).

Longer-term remediation and best practice

1. Patch management and plugin hygiene
   Remove unused plugins. Keep required plugins updated and test upgrades in staging.
2. Harden SSO integrations
   Treat SSO connectors as critical infrastructure. Use least privilege for role mappings and avoid automatic promotion to admin.
3. Principle of least exposure
   Disable test/debug endpoints in production.
4. Defense in depth
   Combine gateway rules, host restrictions, least-privilege WordPress users, 2FA, and monitoring.
5. Incident response readiness
   Keep documented incident response procedures, backups, and tested restore processes.
6. Logging and detection
   Centralize logs and alert on suspicious patterns such as unauthenticated access to plugin endpoints.

If you think you were exploited — what to do now

1. Isolate the affected site
   Put the site into maintenance mode or isolate it from networks where feasible.
2. Preserve logs and evidence
   Export access logs, error logs and relevant system logs for investigation.
3. Rotate secrets and credentials
   Rotate API keys, SSO client secrets and admin passwords that might have been exposed. Coordinate changes with identity providers to avoid disruption.
4. Full compromise scan
   Run a thorough malware and integrity scan. Engage a competent incident responder if needed.
5. Rebuild from known-good backups
   If you cannot guarantee removal of malicious artifacts, restore from a trusted backup and re-harden the environment.
6. Post-incident actions
   Identify root cause, patch or remove the vulnerable plugin, and document lessons learned.

Monitoring and detection guidance (practical)

• Create an alert for any unauthenticated 200 response containing substrings such as moym or test_attributes in the response body.
• Alert on repeated failed login attempts following anomalous exposure events.
• If using a centralized SIEM, correlate (access to vulnerable endpoint) + (subsequent successful login within 48 hours from same IP) => high priority.

Why virtual patching matters here

When a vendor patch is not yet available, virtual patching at your gateway or server is the fastest way to reduce risk. Blocking the vulnerable request paths prevents unauthenticated disclosure without changing plugin code, buying time for proper testing and deployment of a permanent fix.

Communication plan for managed sites and stakeholders

If you manage sites for clients or internal teams, communicate clearly and promptly:

• Notify site owners that YM SSO Login ≤1.1.7 is affected and immediate mitigation is advised.
• Explain the actions you will take: audit plugin presence, enforce gateway/server rules, monitor logs, and coordinate patching when available.
• If you manage SSO integrations, coordinate with identity providers before rotating client secrets to avoid service disruption.

Example server-level quick fixes (conceptual)

Test these on staging before applying in production:

• Apache (.htaccess) — deny access to identifiable plugin PHP files by returning 403 for direct requests.
• nginx — inspect query string and return 403 when action=moym_display_test_attributes is present in calls to admin-ajax.php.

Keep rules as narrow as possible to avoid blocking legitimate admin operations.

Recommended checklist for administrators

1. Search all sites for the plugin and identify version numbers.
2. If plugin exists and version ≤ 1.1.7, immediately do one or more of:
   • Deactivate and remove the plugin (if feasible), OR
   • Apply gateway/server rules to block the vulnerable action/endpoint, OR
   • Restrict plugin file access via server rules / IP restrictions.
3. Audit logs for access to plugin endpoints over the past 30 days.
4. Rotate SSO client secrets if you find suspicious activity or if the plugin is integral to your SSO flow.
5. Prepare a remediation plan: replace the plugin with an alternative integration or coordinate patching with the vendor when available.
6. Enable monitoring for related indicators (suspicious admin logins, new admin accounts, unexpected file changes).
7. Document actions and communicate to stakeholders.

Final notes and responsible disclosure

Treat this advisory as time-sensitive. The vulnerability permits unauthenticated access to internal attributes and should be mitigated promptly. Avoid public disclosure of exploit details; share technical proof responsibly with trusted parties or through a responsible disclosure process.

If you need assistance with triage, rule creation, or auditing for this issue, engage experienced security professionals familiar with WordPress hardening and incident response.

From a Hong Kong security practitioner: prioritise containment and evidence preservation, and coordinate changes carefully to avoid service disruption while reducing your exposure window.