The Minify HTML plugin for WordPress is vulnerable to Regular Expression Denial of Service (ReDoS) in all versions up to, and including, 2.1.10. This is due to processing user-supplied input as a regular expression. This makes it possible for unauthenticated attackers to create comments that can cause catastrophic backtracking and break pages.
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.