Vulnerabilities affecting this package (0)
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This package is not known to be affected by vulnerabilities.
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Vulnerabilities fixed by this package (1)
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VCID-ug8h-p8kf-t7e1
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Possible request smuggling in HTTP/2 due missing validation
### Impact
If a Content-Length header is present in the original HTTP/2 request, the field is not validated by `Http2MultiplexHandler` as it is propagated up. This is fine as long as the request is not proxied through as HTTP/1.1.
If the request comes in as an HTTP/2 stream, gets converted into the HTTP/1.1 domain objects (`HttpRequest`, `HttpContent`, etc.) via `Http2StreamFrameToHttpObjectCodec `and then sent up to the child channel's pipeline and proxied through a remote peer as HTTP/1.1 this may result in request smuggling.
In a proxy case, users may assume the content-length is validated somehow, which is not the case. If the request is forwarded to a backend channel that is a HTTP/1.1 connection, the Content-Length now has meaning and needs to be checked.
An attacker can smuggle requests inside the body as it gets downgraded from HTTP/2 to HTTP/1.1. A sample attack request looks like:
```
POST / HTTP/2
:authority:: externaldomain.com
Content-Length: 4
asdfGET /evilRedirect HTTP/1.1
Host: internaldomain.com
```
Users are only affected if all of this is `true`:
* `HTTP2MultiplexCodec` or `Http2FrameCodec` is used
* `Http2StreamFrameToHttpObjectCodec` is used to convert to HTTP/1.1 objects
* These HTTP/1.1 objects are forwarded to another remote peer.
### Patches
This has been patched in 4.1.60.Final
### Workarounds
The user can do the validation by themselves by implementing a custom `ChannelInboundHandler` that is put in the `ChannelPipeline` behind `Http2StreamFrameToHttpObjectCodec`.
### References
Related change to workaround the problem: https://github.com/Netflix/zuul/pull/980
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CVE-2021-21295
GHSA-wm47-8v5p-wjpj
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