CVE-2021-21295 Detail

Current Description

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`.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score matches with CNA score
CNA:  GitHub, Inc.
Base Score:  5.9 MEDIUM
Vector:  CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: The NVD and the CNA have provided the same score. When this occurs only the CNA information is displayed, but the Acceptance Level icon for the CNA is given a checkmark to signify NVD concurrence.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://github.com/Netflix/zuul/pull/980 Patch  Third Party Advisory 
https://github.com/netty/netty/commit/89c241e3b1795ff257af4ad6eadc616cb2fb3dc4 Patch  Vendor Advisory 
https://github.com/netty/netty/security/advisories/GHSA-wm47-8v5p-wjpj Third Party Advisory 
https://lists.apache.org/thread.html/r02e467123d45006a1dda20a38349e9c74c3a4b53e2e07be0939ecb3f@%3Cdev.ranger.apache.org%3E Mailing List  Third Party Advisory 
https://lists.apache.org/thread.html/r040a5e4d9cca2f98354b58a70b27099672276f66995c4e2e39545d0b@%3Cissues.hbase.apache.org%3E
https://lists.apache.org/thread.html/r15f66ada9a5faf4bac69d9e7c4521cedfefa62df9509881603791969@%3Cjira.kafka.apache.org%3E
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https://www.debian.org/security/2021/dsa-4885

Weakness Enumeration

CWE-ID CWE Name Source
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling') Provider acceptance level GitHub, Inc.  

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Change History

32 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-21295
NVD Published Date:
03/09/2021
NVD Last Modified:
05/11/2021
Source:
GitHub, Inc.