www/varnish7 -- Denial of Service in HTTP/2

Varnish Development Team reports:

A denial of service attack can be performed on Varnish Cache servers that have the HTTP/2 protocol turned on. An attacker can create a large number of streams and immediately reset them without ever reaching the maximum number of concurrent streams allowed for the session, causing the Varnish server to consume unnecessary resources processing requests for which the response will not be delivered.

This attack is a variant of the HTTP/2 Rapid Reset Attack, which was partially handled as VSV00013.

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