Improperly Implemented Security Check for Standard Affecting dnsmasq package, versions <2.82-1ubuntu2


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.44% (75th percentile)

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  • Snyk IDSNYK-UBUNTU2204-DNSMASQ-2790884
  • published19 Jan 2021
  • disclosed20 Jan 2021

Introduced: 19 Jan 2021

CVE-2020-25686  (opens in a new tab)
CWE-358  (opens in a new tab)

How to fix?

Upgrade Ubuntu:22.04 dnsmasq to version 2.82-1ubuntu2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream dnsmasq package and not the dnsmasq package as distributed by Ubuntu. See How to fix? for Ubuntu:22.04 relevant fixed versions and status.

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.

CVSS Scores

version 3.1