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Cache poisoning is where an HTTP request tricks a web server into responding with a harmful resource. This resource will have the same cache key as a normal, clean request, making it indistinguishable. This contaminated resource will then get cached and served to others. CPDoS attack poses an increased risk. Even attackers can disable critical messages or security alerts on mission-critical websites like official governmental or online banking websites. An effective countermeasure against CPDoS attacks is deploying WAF (Web Application Firewall)