CVE-2026-11964: Unknown User Registration & Membership

Critical severity, CVSS 9.1. EPSS: 0.5% chance of exploitation in the next 30 days.

The User Registration & Membership WordPress plugin before 5.2.2 does not verify the authenticity of incoming payment-provider webhook notifications before acting on them, allowing unauthenticated attackers to forge a payment-approved event and activate a paid membership subscription without completing a real payment.

Affected products

• Unknown User Registration & Membership: before 5.2.2 (fixed in 5.2.2)

Published 2026-07-13. Last modified 2026-07-13.