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MediumFix available

python-hpack security update

Type: advisorySources: OSV

hpack provides a simple Python interface to the HPACK compression algorithm,used to compress HTTP headers in HTTP/2.Used by some of the most populer HTTP/2 implementations in Python,HPACK offers a great Python interface as well as optional upgrade to optimised C-based compression routines from nghttp2. Security Fix(es): hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.(CVE-2026-59980)

Products
python-hpack
Affected versions
Not specified
Fixed versions
4.0.0-3.oe2403sp4
CVEs
CVE-2026-59980
Confirmed fixed CVEs
Not specified
Updated in this feed
30 Oct 2026, 20:39 UTC · Revision 1

Source evidence

python-hpack security update

core-osv · Original source

Published 16 Oct 2026, 11:58 UTC

hpack provides a simple Python interface to the HPACK compression algorithm,used to compress HTTP headers in HTTP/2.Used by some of the most populer HTTP/2 implementations in Python,HPACK offers a great Python interface as well as optional upgrade to optimised C-based compression routines from nghttp2. Security Fix(es): hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.(CVE-2026-59980)

osv:OESA-2026-4242

python-hpack

Fixed versions: 4.0.0-3.oe2403sp4

Complete source record
{
  "id": "b00706d960b96015f703769f024047fb209c00e4b5367891fa5c02cf03416164",
  "url": "https://osv.dev/vulnerability/OESA-2026-4242",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "python-hpack security update",
    "summary": "hpack provides a simple Python interface to the HPACK compression algorithm,used to compress HTTP headers in HTTP/2.Used by some of the most populer HTTP/2 implementations in Python,HPACK offers a great Python interface as well as optional upgrade to optimised C-based compression routines from nghttp2. Security Fix(es): hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.(CVE-2026-59980)",
    "evidence": "osv:OESA-2026-4242",
    "products": [
      {
        "name": {
          "value": "python-hpack",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.0.0-3.oe2403sp4",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "OESA-2026-4242",
      "aliases": [
        "OESA-2026-4242"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "4.0.0-3.oe2403sp4"
                }
              ]
            }
          ],
          "package": {
            "name": "python-hpack",
            "purl": "pkg:rpm/openEuler/python-hpack&distro=openEuler-24.03-LTS-SP4",
            "ecosystem": "openEuler:24.03-LTS-SP4"
          },
          "database_specific": {
            "source": "https://repo.openeuler.org/security/data/osv/OESA-2026-4242.json"
          },
          "ecosystem_specific": {
            "src": [
              "python-hpack-4.0.0-3.oe2403sp4.src.rpm"
            ],
            "noarch": [
              "python3-hpack-4.0.0-3.oe2403sp4.noarch.rpm"
            ]
          }
        }
      ],
      "modified": "2026-10-16T12:15:04.189697601Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-59980"
      ],
      "references": [
        "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-4242",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-59980"
      ],
      "provider_metadata": {
        "severity": "Medium"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-59980",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 340741,
  "published_at": "2026-10-16T11:58:31+00:00"
}