CVE-2016-6581: High severity python hpack vulnerability
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.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2016-6581?
CVE-2016-6581 has a medium severity rating due to its potential for denial of service attacks.
How do I fix CVE-2016-6581?
To fix CVE-2016-6581, upgrade the Python HPACK library to version 2.3.0 or higher.
What versions of the HPACK library are affected by CVE-2016-6581?
Versions of the HPACK library between 1.0.0 and 2.2.0 are affected by CVE-2016-6581.
What type of attack does CVE-2016-6581 relate to?
CVE-2016-6581 relates to a denial of service attack, specifically an HPACK Bomb attack.
Can CVE-2016-6581 affect any software using PHP?
CVE-2016-6581 specifically affects implementations using the Python HPACK library, not PHP.