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CVE-2021-21295

Common vulnerabilities & exposures (CVE)

CVE databaseCVE database blogpostRelease & EoL database
 
Published at: - 09-03-2021 08:15
Last modified: - 12-05-2022 04:34
Total changes: - 31

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`.

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
High
Attack complexity
Network
Attack vector
None
Availability
None
Confidentiality
High
Integrity
None
Privileges required
Unchanged
Scope
None
User interaction
5.9
Base score
2.2
3.6
Exploitability score
Impact score
 

Verification logic

OR
OR
vendor=netty AND product=netty AND versionEndExcluding=4.1.60
OR
vendor=netapp AND product=oncommand_workflow_automation AND version=-
vendor=netapp AND product=oncommand_api_services AND version=-
OR
vendor=Debian AND product=debian_linux AND version=10.0
OR
vendor=quarkus AND product=quarkus AND versionEndIncluding=1.13.7
OR
vendor=apache AND product=kudu AND versionEndExcluding=1.16.0
vendor=apache AND product=zookeeper AND version=3.5.9
OR
vendor=oracle AND product=communications_cloud_native_core_policy AND version=1.14.0
 

Reference

 


Keywords

NVD

 

CVE-2021-21295

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures

 

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