CVE-2021-3448

Name	CVE-2021-3448
Description	A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
dnsmasq (PTS)	buster, buster (security)	2.80-1+deb10u1	vulnerable
	bullseye	2.85-1	fixed
	bookworm	2.89-1	fixed
	trixie	2.90-2	fixed
	sid	2.90-3	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
dnsmasq	source	(unstable)	2.85-1

Notes

[buster] - dnsmasq <postponed> (Revisit once upstream has backported to 2.80)
[stretch] - dnsmasq <postponed> (Probably easier to base the patch on a backported version)
https://bugzilla.redhat.com/show_bug.cgi?id=1939368
https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=74d4fcd756a85bc1823232ea74334f7ccfb9d5d2