https://www.bleepingcomputer.com/news/security/new-cpdos-web-cache-poisoning-attacks-impact-sites-using-popular-cdns/

Details have emerged about a new class of web cache poisoning attacks that could be used to deny users access to resources delivered through a content delivery network (CDN).

Named Cache-Poisoned Denial of Service (CPDoS), the new method has several variations and works by sending an HTTP request with a malformed header.