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CriticalFix available

Integer overflow in `hyper`'s parsing of the `Transfer-Encoding` header leads to data loss

Type: advisorySources: OSV

When decoding chunk sizes that are too large, `hyper`'s code would encounter an integer overflow. Depending on the situation, this could lead to data loss from an incorrect total size, or in rarer cases, a request smuggling attack. To be vulnerable, you must be using `hyper` for any HTTP/1 purpose, including as a client or server, and consumers must send requests or responses that specify a chunk size greater than 18 exabytes. For a possible request smuggling attack to be possible, any upstream proxies must accept a chunk size greater than 64 bits.

Products
hyper
Affected versions
Not specified
Fixed versions
0.14.10
CVEs
CVE-2021-32714
Confirmed fixed CVEs
Not specified
Updated in this feed
30 Oct 2026, 08:40 UTC · Revision 1

Source evidence

Integer overflow in `hyper`'s parsing of the `Transfer-Encoding` header leads to data loss

core-osv · Original source

Published 7 Jul 2021, 12:00 UTC

When decoding chunk sizes that are too large, `hyper`'s code would encounter an integer overflow. Depending on the situation, this could lead to data loss from an incorrect total size, or in rarer cases, a request smuggling attack. To be vulnerable, you must be using `hyper` for any HTTP/1 purpose, including as a client or server, and consumers must send requests or responses that specify a chunk size greater than 18 exabytes. For a possible request smuggling attack to be possible, any upstream proxies must accept a chunk size greater than 64 bits.

osv:RUSTSEC-2021-0079

hyper

Fixed versions: 0.14.10

Complete source record
{
  "id": "c62a348deef9ec27da9a295f2797ea69f532fb2442d508c1694ba5a654aaa356",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2021-0079",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Integer overflow in `hyper`'s parsing of the `Transfer-Encoding` header leads to data loss",
    "summary": "When decoding chunk sizes that are too large, `hyper`'s code would encounter an integer overflow. Depending on the situation, this could lead to data loss from an incorrect total size, or in rarer cases, a request smuggling attack. To be vulnerable, you must be using `hyper` for any HTTP/1 purpose, including as a client or server, and consumers must send requests or responses that specify a chunk size greater than 18 exabytes. For a possible request smuggling attack to be possible, any upstream proxies must accept a chunk size greater than 64 bits.",
    "evidence": "osv:RUSTSEC-2021-0079",
    "products": [
      {
        "name": {
          "value": "hyper",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.14.10",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "RUSTSEC-2021-0079",
      "aliases": [
        "CVE-2021-32714",
        "GHSA-5h46-h7hh-c6x9",
        "RUSTSEC-2021-0079"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.14.10"
                }
              ]
            }
          ],
          "package": {
            "name": "hyper",
            "purl": "pkg:cargo/hyper",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2021-0079.json",
            "categories": [],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:02.671544457Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/hyper",
        "https://rustsec.org/advisories/RUSTSEC-2021-0079.html",
        "https://github.com/hyperium/hyper/commit/efd9a9821fd2f1ae04b545094de76a435b62e70f"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-32714",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306323,
  "published_at": "2021-07-07T12:00:00+00:00"
}