CVE-2020-25684

Description

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.

How to fix CVE-2020-25684

To remediate CVE-2020-25684, upgrade the affected package to a fixed version below.

• —upgrade to 2.83-r0 or later
• —upgrade to 2.83-1 or later

Is CVE-2020-25684 being exploited?

Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 2.83-r0
• from 0, < 2.83-1

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2020-25684
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2020-25684