Vulnerability Details : 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.
Vulnerability category: Denial of service
Products affected by CVE-2016-6581
- cpe:2.3:a:python:hpack:1.0:*:*:*:*:*:*:*
- cpe:2.3:a:python:hpack:2.0:*:*:*:*:*:*:*
- cpe:2.3:a:python:hpack:2.1.1:*:*:*:*:*:*:*
- cpe:2.3:a:python:hpack:2.0.1:*:*:*:*:*:*:*
- cpe:2.3:a:python:hpack:2.2:*:*:*:*:*:*:*
- cpe:2.3:a:python:hyper:0.4:*:*:*:*:*:*:*
- cpe:2.3:a:python:hyper:0.6:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2016-6581
0.37%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 56 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2016-6581
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
|---|---|---|---|---|---|---|
|
7.8
|
HIGH | AV:N/AC:L/Au:N/C:N/I:N/A:C |
10.0
|
6.9
|
NIST | |
|
7.5
|
HIGH | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
3.9
|
3.6
|
NIST |
CWE ids for CVE-2016-6581
-
Assigned by: nvd@nist.gov (Primary)
References for CVE-2016-6581
-
https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.html
HPACK Bomb — hpack 3.1.0dev0 documentationMitigation;Vendor Advisory
-
http://www.securityfocus.com/bid/92315
Python HPACK CVE-2016-6581 Remote Denial of Service VulnerabilityThird Party Advisory;VDB Entry
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