Vulnerability-Lookup

OESA-2026-4239 (CVE-2026-59980)

Vulnerability from osv_openeuler – Published: 2026-10-16 11:58 – Updated: 2026-10-16 11:58 – Source website

Summary

python-hpack security update

Details

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)

Severity

6.3 (Medium)


                    
                      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

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-59980	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "noarch": [
          "python3-hpack-4.0.0-2.oe2203sp4.noarch.rpm"
        ],
        "src": [
          "python-hpack-4.0.0-2.oe2203sp4.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "python-hpack",
        "purl": "pkg:rpm/openEuler/python-hpack\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.0.0-2.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Medium"
  },
  "details": "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.\r\n\r\nSecurity Fix(es):\n\nhpack 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)",
  "id": "OESA-2026-4239",
  "modified": "2026-10-16T11:58:29Z",
  "published": "2026-10-16T11:58:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-4239"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59980"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "python-hpack security update",
  "upstream": [
    "CVE-2026-59980"
  ]
}

CVE-2026-59980 (GCVE-0-2026-59980)

Vulnerability from cvelistv5 – Published: 2026-09-23 22:07 – Updated: 2026-09-24 13:25

Title

hpack: Unbounded variable integer decoding can cause run-away computation on malformed input

Summary

Severity

6.3 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-24 13:24 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 8026 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/python-hyper/hpack/security/ad…	x_refsource_CONFIRM
https://github.com/python-hyper/hpack/commit/8cfb…	x_refsource_MISC
https://cs.opensource.google/go/x/net/+/master:ht…	x_refsource_MISC
https://docs.rs/http2/0.5.19/src/http2/hpack/deco…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
python-hyper	hpack	Affected: < 4.2.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-59980",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-24T13:24:31.887152Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-24T13:25:08.900Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "hpack",
          "vendor": "python-hyper",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.2.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-23T22:07:35.095Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/python-hyper/hpack/security/advisories/GHSA-8v8h-hg4w-mvq2"
        },
        {
          "name": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/python-hyper/hpack/commit/8cfb02c547740e16dbfe7aba77bad84b297cec2c"
        },
        {
          "name": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://cs.opensource.google/go/x/net/+/master:http2/hpack/hpack.go;l=468;drc=8e2b117aee74f6b86c207a808b0255de45c0a18a"
        },
        {
          "name": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://docs.rs/http2/0.5.19/src/http2/hpack/decoder.rs.html#403"
        }
      ],
      "source": {
        "advisory": "GHSA-8v8h-hg4w-mvq2",
        "discovery": "UNKNOWN"
      },
      "title": "hpack: Unbounded variable integer decoding can cause run-away computation on malformed input"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-59980",
    "datePublished": "2026-09-23T22:07:35.095Z",
    "dateReserved": "2026-07-07T19:41:00.004Z",
    "dateUpdated": "2026-09-24T13:25:08.900Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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