varnish -- HTTP/2 Request Forgery Vulnerability

Varnish Cache Project reports:

A request forgery attack can be performed on Varnish Cache servers that have the HTTP/2 protocol turned on. An attacker may introduce characters through the HTTP/2 pseudo-headers that are invalid in the context of an HTTP/1 request line, causing the Varnish server to produce invalid HTTP/1 requests to the backend. This may in turn be used to successfully exploit vulnerabilities in a server behind the Varnish server.

[source]