Inconsistent interpretation of HTTP requests in Netty - CVE-2021-21295

CSH
CYBERSECURITY HELP
Sign In REGISTER
 
Main Vulnerability Database Vulnerabilities #VU51836

Inconsistent interpretation of HTTP requests in Netty - CVE-2021-21295

Published: April 1, 2021 / Updated: February 11, 2025


Vulnerability identifier: #VU51836
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2021-21295
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability: No public exploit available
Vendor: Netty project
Affected software:
Netty

Detailed vulnerability description

The vulnerability allows a remote attacker to preform HTTP request smuggling attacks.

The vulnerability exists due to improper validation of HTTP requests in io.netty:netty-codec-http2 when converting HTTP/2 to HTTP/1 streams. A remote attacker can send a specially crafted HTTP request to the server and smuggle arbitrary HTTP headers.

Successful exploitation of vulnerability may allow an attacker to poison HTTP cache and perform phishing attacks.


How to mitigate CVE-2021-21295

Install updates from vendor's website.

Sources