CVE-2021-21290 — Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files

Affected: netty

Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty before version 4.1.59.Final there is a vulnerability on Unix-like systems involving an insecure temp file. 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 is enabled. On unix-like systems, the temporary directory is shared between all user. As such, writing to this directory using APIs that do not explicitly set the file/directory permissions can lead to information disclosure. Of note, this does not impact modern MacOS Operating Systems. 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--". Thus, if sensitive information is written to this file, other local users can read this information. This is the case in netty's "AbstractDiskHttpData" is vulnerable. This has been fixed in version 4.1.59.Final. As a workaround, one may specify your own "java.io.tmpdir" when you start the JVM or use "DefaultHttpDataFactory.setBaseDir(...)" to set the directory to something that is only readable by the current user.

USN-6049-1 — netty vulnerabilities

Affected: Ubuntu:Pro:16.04:LTS: netty, Ubuntu:Pro:18.04:LTS: netty, Ubuntu:Pro:20.04:LTS: netty, Ubuntu:22.04:LTS: netty

It was discovered that Netty's Zlib decoders did not limit memory allocations. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. This issue only affected Ubuntu 16.04 ESM and Ubuntu 20.04 ESM. (CVE-2020-11612)

It was discovered that Netty created temporary files with excessive permissions. A local attacker could possibly use this issue to expose sensitive information. This issue only affected Ubuntu 16.04 ESM, Ubuntu 18.04 ESM, and Ubuntu 20.04 ESM. (CVE-2021-21290)

It was discovered that Netty did not properly validate content-length headers. A remote attacker could possibly use this issue to smuggle requests. This issue was only fixed in Ubuntu 20.04 ESM. (CVE-2021-21295, CVE-2021-21409)

It was discovered that Netty's Bzip2 decompression decoder did not limit the decompressed output data size. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. This issue only affected Ubuntu 18.04 ESM, Ubuntu 20.04 ESM, Ubuntu 22.04 LTS, and Ubuntu 22.10. (CVE-2021-37136)

It was discovered that Netty's Snappy frame decoder function did not limit chunk lengths. A remote attacker could possibly use this issue to cause Netty to exhaust memory via malicious input, leading to a denial of service. (CVE-2021-37137)

It was discovered that Netty did not properly handle control chars at the beginning and end of header names. A rem…

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CVE-2021-21290 — Local Information Disclosure Vulnerability in Netty on Unix-Like systems due temporary files

USN-6049-1 — netty vulnerabilities