HTTP/2 vulnerabilities

An attacker may cause an HTTP/2 endpoint to read arbitrary amounts of header data by sending an excessive number of CONTINUATION frames. Maintaining HPACK state requires parsing and processing all HEADERS and CONTINUATION frames on a connection; when a request's headers exceed MaxHeaderBytes, no memory is allocated to store the excess headers, but they are still parsed. This permits an attacker to cause an HTTP/2 endpoint to read arbitrary amounts of header data, including Huffman-encoded data that is significantly more expensive for the receiver to decode than for an attacker to send. The fix sets a limit on the amount of excess header frames processed before closing a connection.

Uncontrolled resource consumption in HTTP/2 allows an unauthenticated attacker to perform a denial-of-service (DoS) attack over the network.

Allocation of resources without limits or throttling in HTTP/2 allows an unauthorized attacker to deny service over a network.