CVE-2021-43797
HTTP request smuggling in netty
Description
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. Netty prior to version 4.1.71.Final skips control chars when they are present at the beginning / 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. Users should upgrade to version 4.1.71.Final.
How to fix CVE-2021-43797
To remediate CVE-2021-43797, upgrade the affected package to a fixed version below.
- —upgrade to 1:4.1.48-4+deb11u1 or later
- —no fix listed
- —upgrade to 4.1.71.Final or later
- —no fix listed
Is CVE-2021-43797 being exploited?
Low — EPSS is 0.4%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 1:4.1.48-4+deb11u1
- from 0
- >= 4.0.0, < 4.1.71.Final
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |