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CVE-2020-25684

Published: 19 January 2021

A 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.

Priority

Medium

CVSS 3 base score: 3.7

Status

Package Release Status
dnsmasq
Launchpad, Ubuntu, Debian
bionic
Released (2.79-1ubuntu0.2)
focal
Released (2.80-1.1ubuntu1.2)
groovy
Released (2.82-1ubuntu1.1)
hirsute
Released (2.82-1ubuntu2)
impish
Released (2.82-1ubuntu2)
jammy
Released (2.82-1ubuntu2)
precise Ignored
(end of ESM support, was needs-triage)
trusty Needs triage

upstream
Released (2.83)
xenial
Released (2.75-1ubuntu0.16.04.7)