Vulnerability Database

289,599

Total vulnerabilities in the database

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.

CVSS v3:

  • Severity: High
  • Score: 7.5
  • AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v2:

  • Severity: High
  • Score: 7.8
  • AV:N/AC:L/Au:N/C:N/I:N/A:C

CWEs:

Software From Fixed in
python / hpack 2.1.1 2.1.1.x
python / hyper 0.6 0.6.x
python / hpack 2.2 2.2.x
python / hpack 2.0 2.0.x
python / hyper 0.4 0.4.x
python / hpack 2.0.1 2.0.1.x
python / hpack 1.0 1.0.x
hpack 1.0.0 2.3.0