Wallet System for WooCommerce 2.0.0 - 2.7.10 - Subscriber+ Wallet Balance Manipulation via Negative Transfer Amount

The Wallet System for WooCommerce WordPress plugin before 2.8.0 does not validate that a wallet transfer amount is positive, and computes the sender's new balance from a stale snapshot taken before crediting the recipient, allowing an authenticated attacker with Subscriber-level access to mint wallet funds for themselves or drain a specific victim's balance into their own account.