CVE-2016-6581

A HTTP/2 implementation built using any version of the Python HPACK library
between v1.0.0 and v2.2.0 could be targeted for a denial of service attack,
specifically a so-called “HPACK Bomb” attack. This attack occurs when an
attacker inserts a header field that is exactly the size of the HPACK
dynamic header table into the dynamic header table. The attacker can then
send a header block that is simply repeated requests to expand that field
in the dynamic table. This can lead to a gigantic compression ratio of
4,096 or better, meaning that 16kB of data can decompress to 64MB of data
on the target machine.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=833467&gt;