python-httpx2 — security advisory

{
  "id": "8fba7978dca5e377f446b05f1b8faf99fa0d3cf506e9fd74463bbe1b274ff6eb",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-84380",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-84380",
    "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.",
    "evidence": "osv:UBUNTU-CVE-2026-84380",
    "products": [
      {
        "name": {
          "value": "python-httpx2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.5.0-1",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "UBUNTU-CVE-2026-84380",
      "aliases": [
        "UBUNTU-CVE-2026-84380"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "python-httpx2",
            "purl": "pkg:deb/ubuntu/python-httpx2?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "2.5.0-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-84380.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-httpcore2",
                "binary_version": "2.5.0-1"
              },
              {
                "binary_name": "python3-httpx2",
                "binary_version": "2.5.0-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T13:01:13.113932439Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-84380"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-84380",
        "https://www.cve.org/CVERecord?id=CVE-2026-84380",
        "https://github.com/pydantic/httpx2/security/advisories/GHSA-pf96-p4fj-6566",
        "https://github.com/pydantic/httpx2/pull/1137",
        "https://github.com/pydantic/httpx2/commit/829b93a2393212996f613e635261f777d9ec6eab",
        "https://github.com/pydantic/httpx2/releases/tag/v2.11.0"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-84380",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 361275,
  "published_at": "2026-09-02T18:21:00+00:00"
}