{
  "schema_version": "1.4.0",
  "id": "GHSA-ffq8-576r-v26g",
  "modified": "2024-09-20T21:39:26Z",
  "published": "2019-07-05T21:11:05Z",
  "aliases": [
    "CVE-2016-6581"
  ],
  "summary": "HPACK Denial of Service vulnerability (HPACK Bomb)",
  "details": "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.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
    },
    {
      "type": "CVSS_V4",
      "score": "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"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "hpack"
      },
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "1.0.0"
            },
            {
              "fixed": "2.3.0"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2016-6581"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-ffq8-576r-v26g"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/hpack/PYSEC-2017-87.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/python-hyper/hpack"
    },
    {
      "type": "WEB",
      "url": "https://python-hyper.org/hpack/en/latest/security/CVE-2016-6581.html"
    },
    {
      "type": "WEB",
      "url": "https://web.archive.org/web/20200227233559/http://www.securityfocus.com/bid/92315"
    },
    {
      "type": "WEB",
      "url": "http://python-hyper.org/projects/hpack/en/stable/security/CVE-2016-6581.html"
    }
  ],
  "database_specific": {
    "cwe_ids": [],
    "severity": "HIGH",
    "github_reviewed": true,
    "github_reviewed_at": "2020-06-16T21:34:33Z",
    "nvd_published_at": null
  }
}