Solana Pay Vulnerable to Weakness in Transfer Validation Logic

Description

When a Solana Pay transaction is located using a reference key, it may be checked to represent a transfer of the desired amount to the recipient, using the supplied validateTransfer function. An edge case regarding this mechanism could cause the validation logic to validate multiple transfers.

Impact

Most known Solana Pay point of sale applications are currently run on physical point of sale devices, which makes this issue unlikely to occur. However, there may be web-based point of sale applications using the protocol where it may be more likely to occur.

Patches

This issue has been patched as of version 0.2.1. Users of the Solana Pay SDK should upgrade to it.