The Tamara Checkout WordPress plugin through 1.9.9.20 does not verify the order key, a nonce, or any capability on its public payment cancel/fail return URLs, changing a WooCommerce order's status based solely on an attacker-supplied numeric order id, so an unauthenticated attacker can cancel or fail arbitrary orders store-wide by enumerating ids (triggering downstream stock-release and notification side-effects).
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1