HTTP Request Smuggling Affecting io.netty:netty-codec-http package, versions [,4.1.71.Final)



    Attack Complexity Low
    User Interaction Required
    Integrity High

    Threat Intelligence

    EPSS 0.12% (46th percentile)
Expand this section
6.5 medium
Expand this section
6.1 medium
Expand this section
Red Hat
6.5 medium

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk ID SNYK-JAVA-IONETTY-2314893
  • published 10 Dec 2021
  • disclosed 9 Dec 2021
  • credit Unknown

How to fix?

Upgrade io.netty:netty-codec-http to version 4.1.71.Final or higher.


io.netty:netty-codec-http is a network application framework for rapid development of maintainable high performance protocol servers & clients.

Affected versions of this package are vulnerable to HTTP Request Smuggling. Netty currently just skips control characters when these are present at the beginning or end of the header name. It should instead fail fast as these are not allowed by the spec and could lead to HTTP request smuggling. Failing to do the validation might cause netty to "sanitize" header names before it forward these to another remote system when used as proxy. This remote system can't see the invalid usage anymore, and therefore does not do the validation itself.