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CVE-2020-25686

Published: 19 January 2021

A flaw was found in dnsmasq before version 2.83. When receiving a query, dnsmasq does not check for an existing pending request for the same name and forwards a new request. By default, a maximum of 150 pending queries can be sent to upstream servers, so there can be at most 150 queries for the same name. This flaw allows an off-path attacker on the network to substantially reduce the number of attempts that it would have to perform to forge a reply and have it accepted by dnsmasq. This issue is mentioned in the "Birthday Attacks" section of RFC5452. If chained with CVE-2020-25684, 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)