CVE-2021-21299 – Multiple Transfer-Encoding headers misinterprets request payload

https://notcve.org/view.php?id=CVE-2021-21299

hyper is an open-source HTTP library for Rust (crates.io). In hyper from version 0.12.0 and before versions 0.13.10 and 0.14.3 there is a vulnerability that can enable a request smuggling attack. The 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". To determine if vulnerable, all these things must be true: 1) Using hyper as an HTTP server (the client is not affected), 2) Using HTTP/1.1 (HTTP/2 does not use transfer-encoding), 3) Using a vulnerable HTTP proxy upstream to hyper. • https://crates.io/crates/hyper https://github.com/hyperium/hyper/commit/8f93123efef5c1361086688fe4f34c83c89cec02 https://github.com/hyperium/hyper/security/advisories/GHSA-6hfq-h8hq-87mf https://portswigger.net/research/http-desync-attacks-request-smuggling-reborn https://rustsec.org/advisories/RUSTSEC-2021-0020.html • CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') •