CVE-2020-25684

NameCVE-2020-25684
DescriptionA flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However, it does not use the address/port to retrieve the exact forwarded query, substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452, which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686, the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDSA-4844-1
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
dnsmasq (PTS)stretch2.76-5+deb9u2vulnerable
stretch (security)2.76-5+deb9u1vulnerable
buster2.80-1vulnerable
buster (security)2.80-1+deb10u1fixed
bullseye, sid2.84-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
dnsmasqsourcebuster2.80-1+deb10u1DSA-4844-1
dnsmasqsource(unstable)2.83-1

Notes

https://www.openwall.com/lists/oss-security/2021/01/19/1
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=257ac0c5f7732cbc6aa96fdd3b06602234593aca

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