GHSA-wm47-8v5p-wjpj Possible request smuggling in HTTP/2 due missing validation

• Maven io.netty:netty-codec-http2: >= 4.0.0, < 4.1.60.Final → fixed in 4.1.60.Final • Maven org.jboss.netty:netty: < 4.0.0 (no fix yet) • Maven io.netty:netty: < 4.0.0 (no fix yet)

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