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CVE-2021-21295


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`.


Published

2021-03-09T19:15:12.657

Last Modified

2024-11-21T05:47:57.530

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 5.9 (MEDIUM)

CVSSv2 Vector

AV:N/AC:H/Au:N/C:N/I:P/A:N

  • Access Vector: NETWORK
  • Access Complexity: HIGH
  • Authentication: NONE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

4.9

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-444
  • Type: Primary
    CWE-444

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application netty netty < 4.1.60 Yes
Application netapp oncommand_api_services - Yes
Application netapp oncommand_workflow_automation - Yes
Operating System debian debian_linux 10.0 Yes
Application quarkus quarkus ≤ 1.13.7 Yes
Application apache kudu < 1.16.0 Yes
Application apache zookeeper 3.5.9 Yes
Application oracle communications_cloud_native_core_policy 1.14.0 Yes

References