Package Instance

Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
An attacker that is able to modify Velocity templates may execute arbitrary Java code or run arbitrary system commands with the same privileges as the account running the Servlet container. This applies to applications that allow untrusted users to upload/modify velocity templates running Apache Velocity Engine versions up to 2.2.

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