CVE-2020-25686

Description

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.

How to fix CVE-2020-25686

To remediate CVE-2020-25686, 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-2020-25686 being exploited?

Low — EPSS is 0.5%, 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-2020-25686
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2020-25686