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FKIE_CVE-2026-84380

Vulnerability from fkie_nvd - Published: 2026-09-02 18:21 - Updated: 2026-09-02 19:18
Severity
5.6 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Summary
HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0.
References
security-advisories@github.comhttps://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab
security-advisories@github.comhttps://github.com/pydantic/httpx2/pull/1137
security-advisories@github.comhttps://github.com/pydantic/httpx2/releases/tag/v2.11.0
security-advisories@github.comhttps://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "httpx2",
          "vendor": "pydantic",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.11.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "HTTPX2 is a next generation HTTP client for Python. Prior to 2.11.0, Request._prepare() in src/httpx2/httpx2/_models.py can add a body-derived Content-Length header to a request that already contains a caller-supplied Transfer-Encoding header because its setdefault() processing checks each default header independently rather than treating the two framing headers as mutually exclusive. Fixed-size byte, JSON, form, and known-length multipart bodies can therefore be serialized over HTTP/1.1 with both headers, allowing request smuggling or connection desynchronization when downstream intermediaries disagree about which framing header takes precedence. This issue is fixed in version 2.11.0."
    }
  ],
  "id": "CVE-2026-84380",
  "lastModified": "2026-09-02T19:18:08.113",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.6,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-84380",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-02T18:07:09.850518Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-02T18:21:29.513",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pydantic/httpx2/pull/1137"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pydantic/httpx2/releases/tag/v2.11.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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