CVEvulnerability
CVE-2016-6581
7.5 HIGH
Official page ↗
- Status
- Modified
- Published
- 2017-01-10
- Last modified
- 2026-06-17
- Assigner
- [email protected]
- CVSS 3.0 ([email protected])
- 7.5 HIGH — CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CVSS 2.0 ([email protected])
- 7.8 HIGH — AV:N/AC:L/Au:N/C:N/I:N/A:C
- Weaknesses
- CWE-399
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.
Affected configurations
• python hpack 1.0
• python hpack 2.0
• python hpack 2.0.1
• python hpack 2.1.1
• python hpack 2.2
• python hyper 0.4
• python hyper 0.6
Related
Weakness · not in database (1)
References
- http://www.securityfocus.com/bid/92315 Third Party Advisory, VDB Entry
- https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.html Mitigation, Vendor Advisory
- http://www.securityfocus.com/bid/92315 Third Party Advisory, VDB Entry
- https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.html Mitigation, Vendor Advisory