CVE-2026-66712

The Simple Membership WordPress plugin before version 4.7.8 does not verify whether user creation failed during registration before using the returned value as a user ID to update an account. This allows unauthenticated attackers to overwrite the primary administrator's account data (including the email address) and take over that account through the password reset flow.

The Simple Membership WordPress plugin before 4.7.7 does not verify that a PayPal payment notification was sent to the site's own configured merchant account before activating a membership. This allows unauthenticated users to activate or extend a membership using a payment made to an arbitrary PayPal account they control.

The Simple Membership WordPress plugin before version 4.7.8 does not sanitize a subscriber name value received from an unauthenticated payment approval request, nor escape it when displaying it in the administration dashboard. This allows unauthenticated attackers to store arbitrary JavaScript that executes in an administrator's session.

The Simple Membership WordPress plugin before version 4.7.5 does not verify the authenticity of Stripe webhook requests when no signing secret is configured, nor escapes a value taken from them before outputting it in an administrator notice, allowing unauthenticated attackers to inject arbitrary web scripts that execute in the context of a logged-in administrator.

There is an unauthenticated Cross Site Scripting (XSS) vulnerability in Simple Membership versions <= 4.7.2. An attacker can exploit this flaw to inject malicious scripts.

Simple Membership versions up to 4.7.1 have a vulnerability in access control that allows unauthorized access.