CVE-2021-20235

Name	CVE-2021-20235
Description	There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.
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-2588-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
zeromq3 (PTS)	buster, buster (security)	4.3.1-4+deb10u2	vulnerable
	bullseye	4.3.4-1	fixed
	bookworm	4.3.4-6	fixed
	sid, trixie	4.3.5-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
zeromq3	source	stretch	4.2.1-4+deb9u4		DLA-2588-1
zeromq3	source	(unstable)	4.3.3-1

Notes

[buster] - zeromq3 <no-dsa> (Minor issue)
https://github.com/zeromq/libzmq/pull/3902
https://github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=21984