python-hyper/hpack · Security
HPACK Denial of Service vulnerability (HPACK Bomb)
- GHSA ID
- GHSA-ffq8-576r-v26g
- CVE ID
- CVE-2016-6581
- Severity
- high
- Published
- Updated
- CVSS
- 7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CVSS v3
- 7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CVSS v4
- 8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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.
References
- https://nvd.nist.gov/vuln/detail/CVE-2016-6581 ↗
- https://github.com/advisories/GHSA-ffq8-576r-v26g ↗
- http://python-hyper.org/projects/hpack/en/stable/security/CVE-2016-6581.html ↗
- https://github.com/pypa/advisory-database/tree/main/vulns/hpack/PYSEC-2017-87.yaml ↗
- https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.html ↗
- https://web.archive.org/web/20200227233559/http://www.securityfocus.com/bid/92315 ↗