{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.11.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "829b93a2393212996f613e635261f777d9ec6eab"
            },
            {
              "fixed": "2b13fa92e4181d5e0f56772205360b2aa12f109d"
            }
          ],
          "repo": "https://github.com/pydantic/httpx2",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-pf96-p4fj-6566"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-444"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84380.json"
  },
  "details": "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",
  "modified": "2026-09-04T03:30:54.319970481Z",
  "published": "2026-09-02T17:58:55.520Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pydantic/httpx2/releases/tag/v2.11.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84380.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-84380"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab"
    },
    {
      "type": "FIX",
      "url": "https://github.com/pydantic/httpx2/pull/1137"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "HTTPX2: Conflicting Content-Length and Transfer-Encoding headers can be auto-generated"
}