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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWZmcTgtNTc2ci12MjZn

HPACK Denial of Service vulnerability (HPACK Bomb)

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.

Permalink: https://github.com/advisories/GHSA-ffq8-576r-v26g
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWZmcTgtNTc2ci12MjZn
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: over 5 years ago
Updated: 2 months ago

CVSS Score: 7.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Percentage: 0.00096
EPSS Percentile: 0.41537

Identifiers: GHSA-ffq8-576r-v26g, CVE-2016-6581
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

Blast Radius: 28.3

Affected Packages