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.

References[email protected]/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/[email protected]/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/


Source: MITRE

Published: 2021-01-20

Updated: 2022-02-14

Risk Information


Base Score: 4.3

Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N

Impact Score: 2.9

Exploitability Score: 8.6

Severity: MEDIUM


Base Score: 3.7

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Impact Score: 1.4

Exploitability Score: 2.2

Severity: LOW