CVE-2021-21290
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.
Vulnerability Summary
CVSS v3 Score
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v2 Score
AV:L/AC:M/Au:N/C:P/I:N/A:N
EPSS Score (Exploitation Probability)
This vulnerability has a 1.78% probability of being exploited in the next 30 days, ranking higher than 75% of all scored CVEs.
Related Vulnerabilities
Same Weakness Type(CWE-378, CWE-379)
A vulnerability has been identified in SINEMA Remote Connect Server (All versions < V3.2 SP1). The affected application does not properly assign rights to temporary files created during its update process. This could allow an authenticated attacker with the 'Manage firmware updates' role to escalate their privileges on the underlying OS level.
Netty is an open-source, asynchronous event-driven network application framework. The package `io.netty:netty-codec-http` prior to version 4.1.77.Final contains an insufficient fix for CVE-2021-21290. 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. This only impacts applications running on Java version 6 and lower. Additionally, this vulnerability impacts code running on Unix-like systems, and very old versions of Mac OSX and Windows as they all share the system temporary directory between all users. Version 4.1.77.Final contains a patch for this vulnerability. As a workaround, specify one's own `java.io.tmpdir` when starting the JVM or use DefaultHttpDataFactory.setBaseDir(...) to set the directory to something that is only readable by the current user.
Similar SeverityMEDIUM
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