Multiple Transfer-Encoding headers misinterprets request payload

{
  "id": "2415d7e58dd044463af5173154936bc240f17028c6e73814250220a4f7695907",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2021-0020",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Multiple Transfer-Encoding headers misinterprets request payload",
    "summary": "hyper's HTTP server code had a flaw that incorrectly understands some requests with multiple transfer-encoding headers to have a chunked payload, when it should have been rejected as illegal. This combined with an upstream HTTP proxy that understands the request payload boundary differently can result in \"request smuggling\" or \"desync attacks\".",
    "evidence": "osv:RUSTSEC-2021-0020",
    "products": [
      {
        "name": {
          "value": "hyper",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.12.36",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "0.13.10",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "0.14.3",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "RUSTSEC-2021-0020",
      "aliases": [
        "CVE-2021-21299",
        "GHSA-6hfq-h8hq-87mf",
        "RUSTSEC-2021-0020"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.12.0"
                },
                {
                  "fixed": "0.12.36"
                },
                {
                  "introduced": "0.13.0-0"
                },
                {
                  "fixed": "0.13.10"
                },
                {
                  "introduced": "0.14.0-0"
                },
                {
                  "fixed": "0.14.3"
                }
              ]
            }
          ],
          "package": {
            "name": "hyper",
            "purl": "pkg:cargo/hyper",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2021-0020.json",
            "categories": [
              "format-injection"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:04.410731844Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/hyper",
        "https://rustsec.org/advisories/RUSTSEC-2021-0020.html",
        "https://github.com/hyperium/hyper/commit/8f93123efef5c1361086688fe4f34c83c89cec02"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-21299",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306343,
  "published_at": "2021-02-05T12:00:00+00:00"
}