Simple Membership accepts PayPal notifications for the wrong merchant before 4.7.7
Simple Membership before 4.7.7 processes a PayPal Standard IPN without verifying that its merchant or receiver email matches the site's configured PayPal account. An unauthenticated attacker can pay an account they control and use the notification to activate or extend a membership although the site owner received no payment. Version 4.7.7 adds merchant and receiver-email validation. The public IPN endpoint, exact parameter names, membership binding and handler function are not disclosed.
- Component
- Simple Membership
- Plugin slug
simple-membership- Affected
- < 4.7.7
- Safe version
4.7.7- Published
- Aug 06, 2026
This CVE was published Aug 06, 2026 and is one of 34 known issues for this plugin.
Update, patch or deactivate.
Update Simple Membership to 4.7.7 or later. Reconcile activated or extended memberships against payments received by the site's configured PayPal account.
A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical description
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, allowing unauthenticated users to activate or extend a membership using a payment made to an arbitrary PayPal account they control.
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N