Simple Membership <= 4.7.5 - Missing Authorization to Unauthenticated Arbitrary Member Account Deactivation via Forged Stripe 'charge.refunded' Webhook

The Simple Membership plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 4.7.5. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for unauthenticated attackers to deactivate arbitrary member accounts by forging a charge.refunded webhook event containing a victim's subscription ID, setting the target member's account_state to 'inactive' and triggering cancellation hooks, transaction-record status changes, and cancellation notification emails. This vulnerability is exploitable only on installations where no Stripe webhook signing secret has been configured, which is the default out-of-the-box state; sites that have configured the stripe-webhook-signing-secret option are routed to the properly verified HMAC path and are not affected.

This one needs no account at all, which puts it outside what login hardening can reach; WordSec's login security narrows the account-level paths around it, and the firewall is what inspects the request itself. None of that substitutes for the fix: Simple Membership 4.7.6 closes this, and updating the plugin is the step that ends it.

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