GHSA-5GMM-HJFJ-8FF7 Paymenter has a credit-refund double-spend race condition in service downgrade (doUpgrade)

Summary The service downgrade implementation in app/Livewire/Services/Upgrade.php::doUpgrade executes a proration calculation and a subsequent user credit refund without any transactional safety or database locks. The only concurrency check relies on an unisolated database query checking for...