Information Disclosure Affecting io.netty:netty-handler package, versions [4.0.0.Final, 4.1.59.Final)



    Attack Complexity Low
    Confidentiality High

    Threat Intelligence

    EPSS 0.05% (13th percentile)
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5.5 medium
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Red Hat
6.2 medium

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  • Snyk ID SNYK-JAVA-IONETTY-1082235
  • published 9 Feb 2021
  • disclosed 9 Feb 2021
  • credit Jonathan Leitschuh

How to fix?

Upgrade io.netty:netty-handler to version 4.1.59.Final or higher.


io.netty:netty-handler is a library that provides an asynchronous event-driven network application framework and tools for rapid development of maintainable high performance and high scalability protocol servers and clients. In other words, Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients. It greatly simplifies and streamlines network programming such as TCP and UDP socket server.

Affected versions of this package are vulnerable to Information Disclosure via the AbstractDiskHttpData method, and on Unix-like systems.

When netty's multipart decoders are used, local information disclosure can occur via the local system temporary directory if temporary storing uploads on the disk are enabled. On unix-like systems, the temporary directory is shared between all users. As such, writing to this directory using API's that do not explicitly set the file/directory permissions can lead to information disclosure. The method File.createTempFile on unix-like systems creates a random file, but, by default will create this file with the permissions -rw-r--r--. Sensitive information is written to this file in AbstractDiskHttpData, and other local users can read it.