{"schema_version":"1.9.0","id":"RUSTSEC-2021-0020","published":"2021-02-05T12:00:00Z","modified":"2026-10-12T18:00:04.410731844Z","aliases":["CVE-2021-21299","GHSA-6hfq-h8hq-87mf"],"summary":"Multiple Transfer-Encoding headers misinterprets request payload","details":"hyper's HTTP server code had a flaw that incorrectly understands some requests\nwith multiple transfer-encoding headers to have a chunked payload, when it\nshould have been rejected as illegal. This combined with an upstream HTTP proxy\nthat understands the request payload boundary differently can result in\n\"request smuggling\" or \"desync attacks\".","affected":[{"package":{"name":"hyper","ecosystem":"crates.io","purl":"pkg:cargo/hyper"},"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"}]}],"ecosystem_specific":{"affected_functions":null,"affects":{"arch":[],"functions":[],"os":[]}},"database_specific":{"categories":["format-injection"],"cvss":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","informational":null,"source":"https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2021-0020.json"}}],"references":[{"type":"PACKAGE","url":"https://crates.io/crates/hyper"},{"type":"ADVISORY","url":"https://rustsec.org/advisories/RUSTSEC-2021-0020.html"},{"type":"WEB","url":"https://github.com/hyperium/hyper/commit/8f93123efef5c1361086688fe4f34c83c89cec02"}],"database_specific":{"license":"CC0-1.0"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}