HTTP Request Smuggling in hyper

published 2020-03-19 6y ago modified 2026-06-17 4mo ago also GHSA-h3qr-rq2j-74w4 , RUSTSEC-2020-0008 , EUVD-2021-1736

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.0%; EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits: 0; none known

An issue was discovered in the hyper crate before 0.12.34 for Rust. HTTP request smuggling can occur. Remote code execution can occur in certain situations with an HTTP server on the loopback interface.

Patch / fix

fixed in 2 distros 1 links 1

crates.io hyper 0.12.34
hyper hyper 0.12.34

rust-hyper Debian 14, Debian 13, Debian 12 0.12.35-1

debian advisories DEBIAN-CVE-2020-35863

rustsec.org/advisories/RUSTSEC-2020-0008.html advisory

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Exploit prediction

2.97% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P
OSV	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
crates.io	hyper	>=0.11.0, <0.12.34	0.12.34

Classification

Weakness

CWE-444 Inconsistent Interpretation of HTTP Requests

References

rustsec.org /advisories/RUSTSEC-2020-0008.html
web, patch, third-party-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2020-35863
advisory
github.com /hyperium/hyper/issues/1925
web, report
github.com /hyperium/hyper
package
crates.io /crates/hyper
package

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.