CVE-2026-10820 Overview
CVE-2026-10820 is an Insecure Direct Object Reference (IDOR) vulnerability in the Paid Membership Plugin for WordPress. The plugin provides ecommerce, user registration, login forms, user profile management, and restrict content functionality. Versions before 4.16.17 fail to verify that the user performing a subscription action owns the targeted subscription. Any authenticated user with Subscriber-level access or higher can cancel other users' active subscriptions by manipulating subscription identifiers in requests. The flaw affects the integrity and availability of subscription data across affected WordPress installations.
Critical Impact
Authenticated low-privileged users can cancel arbitrary subscriptions belonging to other members, disrupting paid memberships and impacting revenue for site operators.
Affected Products
- Paid Membership Plugin for WordPress (Ecommerce, User Registration Form, Login Form, User Profile & Restrict Content) versions before 4.16.17
- WordPress sites using the affected plugin with open registration or Subscriber-level accounts
- Membership-driven ecommerce sites relying on the plugin for subscription lifecycle management
Discovery Timeline
- 2026-06-27 - CVE-2026-10820 published to NVD
- 2026-06-29 - Last updated in NVD database
Technical Details for CVE-2026-10820
Vulnerability Analysis
The vulnerability is an Insecure Direct Object Reference affecting subscription management endpoints. The plugin exposes subscription cancellation functionality that accepts a subscription identifier from the authenticated user. The application does not validate that the current session owner is the legitimate owner of the referenced subscription. As a result, any authenticated user can substitute another member's subscription identifier and trigger a cancellation. The attacker only needs a Subscriber account, which is the lowest privilege level and often available through open registration on membership sites. Exploitation requires no user interaction from the victim and can be performed remotely over the network.
Root Cause
The root cause is missing authorization enforcement on the subscription action handler. The code path processes the subscription identifier submitted with the request without cross-referencing the identifier against the authenticated user's owned subscriptions. Authentication is required, but authorization checks are absent, resulting in broken access control on a sensitive state-changing action.
Attack Vector
An attacker registers or logs in as a Subscriber on the target WordPress site. The attacker enumerates or guesses valid subscription identifiers, which are typically sequential integers. The attacker submits a subscription cancellation request substituting the target's subscription identifier. The plugin processes the request as if the attacker owned the subscription and cancels it. Repeating the process across identifier ranges enables mass cancellation of active memberships.
No verified proof-of-concept code is publicly available. See the WPScan Vulnerability Report for additional technical detail.
Detection Methods for CVE-2026-10820
Indicators of Compromise
- Unexpected subscription status transitions to cancelled for active members not initiated by the account owner
- Web server access logs showing repeated POST requests to plugin subscription action endpoints from a single authenticated Subscriber session
- Sequential access patterns iterating through numeric subscription identifiers within a short window
- Support tickets from members reporting sudden loss of paid access without user action
Detection Strategies
- Audit the plugin's subscription database table for cancellation events and correlate the acting user against the subscription owner
- Compare user_id on the subscription record against the WordPress session user for each cancellation event in logs
- Deploy WordPress audit logging to capture subscription state changes with acting-user context
- Alert on any single authenticated user account triggering multiple cancellations across different subscription owners
Monitoring Recommendations
- Monitor authenticated request rates to plugin AJAX and admin-post endpoints handling subscription actions
- Track new Subscriber account registrations followed by subscription action requests within short intervals
- Forward WordPress and web server logs to a centralized SIEM for correlation of subscription state changes with session identity
- Baseline normal cancellation volume and alert on statistical anomalies
How to Mitigate CVE-2026-10820
Immediate Actions Required
- Upgrade the Paid Membership Plugin to version 4.16.17 or later on all affected WordPress sites
- Review recent subscription cancellations and restore any that cannot be attributed to the legitimate subscription owner
- Temporarily disable open Subscriber registration if the plugin cannot be updated immediately
- Rotate credentials for any accounts suspected of abusing the vulnerability and remove untrusted Subscriber accounts
Patch Information
The vendor released a fix in version 4.16.17 that adds ownership verification before processing subscription cancellation actions. Site administrators should update through the WordPress plugin manager or by replacing the plugin files with the patched release. Refer to the WPScan Vulnerability Report for the authoritative advisory.
Workarounds
- Restrict new user registrations on the site until the plugin is updated
- Apply a Web Application Firewall rule that blocks subscription cancellation requests where the request parameters do not correspond to the authenticated user's owned subscription identifiers
- Manually review and require administrator approval for any cancellation event during the mitigation window
- Limit Subscriber-level accounts to trusted email domains where feasible
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
