CVE-2021-21290

Name	CVE-2021-21290
Description	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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-2555-1, DSA-4885-1, ELA-895-1, ELA-908-1
Debian Bugs	982580

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
netty (PTS)	jessie, jessie (lts)	1:3.2.6.Final-2+deb8u2	fixed
	stretch (security)	1:4.1.7-2+deb9u3	fixed
	stretch (lts), stretch	1:4.1.7-2+deb9u5	fixed
	buster (security), buster, buster (lts)	1:4.1.33-1+deb10u5	fixed
	bullseye (security), bullseye	1:4.1.48-4+deb11u2	fixed
	bookworm (security), bookworm	1:4.1.48-7+deb12u1	fixed
	sid, trixie	1:4.1.48-10	fixed
netty-3.9 (PTS)	jessie, jessie (lts)	3.9.0.Final-1+deb8u2	fixed
	stretch (security)	3.9.9.Final-1+deb9u1	vulnerable
	stretch (lts), stretch	3.9.9.Final-1+deb9u2	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Origin	Debian Bugs
netty	source	jessie	(not affected)
netty	source	stretch	1:4.1.7-2+deb9u3	DLA-2555-1
netty	source	buster	1:4.1.33-1+deb10u2	DSA-4885-1
netty	source	(unstable)	1:4.1.48-2		982580
netty-3.9	source	jessie	3.9.0.Final-1+deb8u2	ELA-908-1
netty-3.9	source	stretch	3.9.9.Final-1+deb9u2	ELA-895-1
netty-3.9	source	(unstable)	(unfixed)

Notes

https://github.com/netty/netty/security/advisories/GHSA-5mcr-gq6c-3hq2
https://github.com/netty/netty/commit/c735357bf29d07856ad171c6611a2e1a0e0000ec
[jessie] - netty <not-affected> (Vulnerable code not present)