Paymenter: Race condition in payWithCredit() enables credit double-spend

Summary

Paymenter is a free and open-source webshop solution for management of hosting services. In versions prior to 1.5.5, the credit payment implementation in app/Livewire/Invoices/Show.php executes a pessimistic row lock (lockForUpdate()) outside of an active database transaction. Because MySQL/MariaDB requires an enclosing transaction to enforce row-level locks, the guard is ineffective. Concurrent payment requests can exploit this race condition to read the same credit balance simultaneously, allowing users to pay multiple invoices using the same credit balance. In database systems like MySQL, a row lock only works inside a formal transaction; without one, the lock is completely ignored. Because there is no active lock, two payment requests sent at the exact same millisecond can look at the database at the same time. Both requests see the original credit balance, decide it is sufficient, and approve the payment. Because the payment processes successfully through ExtensionHelper::addPayment(), the application provisions the corresponding services or digital goods, resulting in direct financial or resource loss to the platform. This issue has been fixed in version 1.5.5.

Timeline

1. Jul 20, 2026, 8:20 PM UTCCVE published
2. Jul 20, 2026, 9:44 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Jul 20, 2026, 9:45 PM UTCRecord last updated

Affected versions

• Paymenter Paymenter

  fixed in 1.5.5

• paymenter/paymenterPackagist

  fixed in 1.5.5

References 1