Inconsistent interpretation of HTTP requests in hyper - CVE-2021-21299
Published: February 5, 2021 / Updated: August 19, 2026
Vulnerability identifier: #VU144331
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-21299
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper interpretation of HTTP headers in transfer-encoding header processing when handling requests with multiple transfer-encoding headers. A remote attacker can send a specially crafted request to cause a denial of service.
Affected software
hyper
How to mitigate CVE-2021-21299
Install security update from vendor's website.
hyper - addressed in versions 0.13.10, 0.14.3