Vulnerability-Lookup

OESA-2025-1496 (CVE-2025-43859)

Vulnerability from osv_openeuler – Published: 2025-05-09 11:08 – Updated: 2026-08-06 11:08 – Source website

Summary

python-h11 security update

Details

h11 is suitable for implementing both servers and clients, and has a pleasantly symmetric API: the events you send as a client are exactly the ones that you receive as a server and vice-versa.

Security Fix(es):

h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.(CVE-2025-43859)

Severity

9.1 (Critical)


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

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2025-43859	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "noarch": [
          "python-h11-help-0.14.0-2.oe2403sp1.noarch.rpm",
          "python3-h11-0.14.0-2.oe2403sp1.noarch.rpm"
        ],
        "src": [
          "python-h11-0.14.0-2.oe2403sp1.src.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "python-h11",
        "purl": "pkg:rpm/openEuler/python-h11\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.14.0-2.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Critical"
  },
  "details": "h11 is suitable for implementing both servers and clients, and has a pleasantly symmetric API: the events you send as a client are exactly the ones that you receive as a server and vice-versa.\r\n\r\nSecurity Fix(es):\n\nh11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11\u0026apos;s parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.(CVE-2025-43859)",
  "id": "OESA-2025-1496",
  "modified": "2026-08-06T11:08:35Z",
  "published": "2025-05-09T11:08:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-1496"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-43859"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "python-h11 security update",
  "upstream": [
    "CVE-2025-43859"
  ]
}

CVE-2025-43859 (GCVE-0-2025-43859)

Vulnerability from cvelistv5 – Published: 2025-04-24 18:15 – Updated: 2025-04-24 19:02

Title

h11 accepts some malformed Chunked-Encoding bodies

Summary

Severity

9.1 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-04-24 19:02 UTC

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Assigner

GitHub_M mitre root Scorecard

References

2 references

URL	Tags
https://github.com/python-hyper/h11/security/advi…	x_refsource_CONFIRM
https://github.com/python-hyper/h11/commit/114803…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
python-hyper	h11	Affected: < 0.16.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-43859",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-04-24T19:02:05.000674Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-04-24T19:02:45.130Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "h11",
          "vendor": "python-hyper",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.16.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11\u0027s parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-04-24T18:15:53.328Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfj"
        },
        {
          "name": "https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36ed"
        }
      ],
      "source": {
        "advisory": "GHSA-vqfr-h8mv-ghfj",
        "discovery": "UNKNOWN"
      },
      "title": "h11 accepts some malformed Chunked-Encoding bodies"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2025-43859",
    "datePublished": "2025-04-24T18:15:53.328Z",
    "dateReserved": "2025-04-17T20:07:08.556Z",
    "dateUpdated": "2025-04-24T19:02:45.130Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}

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.

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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OESA-2025-1496 (CVE-2025-43859)

CVE-2025-43859 (GCVE-0-2025-43859)

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Sightings

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