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
Upstream
Released (2.83)
Ubuntu 21.10 (Impish Indri)
Released (2.82-1ubuntu2)
Ubuntu 21.04 (Hirsute Hippo)
Released (2.82-1ubuntu2)
Ubuntu 20.04 LTS (Focal Fossa)
Released (2.80-1.1ubuntu1.2)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (2.79-1ubuntu0.2)
Ubuntu 16.04 ESM (Xenial Xerus)
Released (2.75-1ubuntu0.16.04.7)
Ubuntu 14.04 ESM (Trusty Tahr) Needs triage