Vulnerability Description
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. If an upstream proxy correctly rejects the illegal transfer-encoding headers, the desync attack cannot succeed. If there is no proxy upstream of hyper, hyper cannot start the desync attack, as the client will repair the headers before forwarding. This is fixed in versions 0.14.3 and 0.13.10. As a workaround one can take the following options: 1) Reject requests that contain a `transfer-encoding` header, 2) Ensure any upstream proxy handles `transfer-encoding` correctly.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Hyper | Hyper | >= 0.12.0, < 0.13.10 |
Related Weaknesses (CWE)
References
- https://crates.io/crates/hyperProductThird Party Advisory
- https://github.com/hyperium/hyper/commit/8f93123efef5c1361086688fe4f34c83c89cec0PatchThird Party Advisory
- https://github.com/hyperium/hyper/security/advisories/GHSA-6hfq-h8hq-87mfThird Party Advisory
- https://portswigger.net/research/http-desync-attacks-request-smuggling-rebornThird Party Advisory
- https://rustsec.org/advisories/RUSTSEC-2021-0020.htmlThird Party Advisory
- https://crates.io/crates/hyperProductThird Party Advisory
- https://github.com/hyperium/hyper/commit/8f93123efef5c1361086688fe4f34c83c89cec0PatchThird Party Advisory
- https://github.com/hyperium/hyper/security/advisories/GHSA-6hfq-h8hq-87mfThird Party Advisory
- https://portswigger.net/research/http-desync-attacks-request-smuggling-rebornThird Party Advisory
- https://rustsec.org/advisories/RUSTSEC-2021-0020.htmlThird Party Advisory
FAQ
What is CVE-2021-21299?
CVE-2021-21299 is a vulnerability with a CVSS score of 4.8 (MEDIUM). 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 ...
How severe is CVE-2021-21299?
CVE-2021-21299 has been rated MEDIUM with a CVSS base score of 4.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-21299?
Check the references section above for vendor advisories and patch information. Affected products include: Hyper Hyper.