The openml/openml.org web application version v2.0.20241110 uses predictable MD5-based tokens for critical user workflows such as signup confirmation, password resets, email confirmation resends, and email change confirmation. These tokens are generated by hashing the current timestamp formatted as %d %H:%M:%S without incorporating any user-specific data or cryptographic randomness. This predictability allows remote attackers to brute-force valid tokens within a small time window, enabling unauthorized account confirmation, password resets, and email change approvals, potentially leading to account takeover.
The product does not properly control the allocation and maintenance of a limited resource.
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.