CVE-2021-21295Medium· 5.9▾ SunlitNetty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.60.Final there i…
▾ Sunlit zone — Low / medium · no exploitation signal
impact 32.5 · likelihood 3.8 · exploitation 0
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Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
19%
Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.60.Final there is a vulnerability that enables request smuggling. 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. For an example attack refer to the linked GitHub Advisory. 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, and these HTTP/1.1 objects are forwarded to another remote peer. This has been patched in 4.1.60.Final As a workaround, the user can do the validation by themselves by implementing a custom ChannelInboundHandler that is put in the ChannelPipeline behind Http2StreamFrameToHttpObjectCodec.
netty < 4.1.60oncommand_api_servicesoncommand_workflow_automationdebian_linux = 10.0quarkus <= 1.13.7kudu < 1.16.0zookeeper = 3.5.9communications_cloud_native_core_policy = 1.14.0Upgrade past the affected range:
netty 4.1.60kudu 1.16.0Connected by shared product, vendor, weakness, or advisory.
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