CVE-2016-6581
Severity CVSS v4.0:
Pending analysis
Type:
CWE-399
Resource Management Errors
Publication date:
10/01/2017
Last modified:
20/04/2025
Description
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.
Impact
Base Score 3.x
7.50
Severity 3.x
HIGH
Base Score 2.0
7.80
Severity 2.0
HIGH
Vulnerable products and versions
| CPE | From | Up to |
|---|---|---|
| cpe:2.3:a:python:hpack:1.0:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hpack:2.0:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hpack:2.0.1:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hpack:2.1.1:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hpack:2.2:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hyper:0.4:*:*:*:*:*:*:* | ||
| cpe:2.3:a:python:hyper:0.6:*:*:*:*:*:*:* |
To consult the complete list of CPE names with products and versions, see this page