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Vulnerability · Published Jan 20, 2021 · Assigned by redhat

CVE-2020-25686

Low 3.7

In plain English

A low-severity security flaw in dnsmasq. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 5.5% (higher than 93% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)3.7Low
Exploit odds (30 days)5.5%top 7.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack tooling1Public PoC

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20dnsmasq2.83-r0ALPINE-CVE-2020-25686
Alpine:v3.21dnsmasq2.83-r0ALPINE-CVE-2020-25686
Alpine:v3.22dnsmasq2.83-r0ALPINE-CVE-2020-25686
Alpine:v3.23dnsmasq2.83-r0ALPINE-CVE-2020-25686
Alpine:v3.24dnsmasq2.83-r0ALPINE-CVE-2020-25686
Debian:12dnsmasq2.83-1DEBIAN-CVE-2020-25686
Debian:13dnsmasq2.83-1DEBIAN-CVE-2020-25686
Debian:14dnsmasq2.83-1DEBIAN-CVE-2020-25686

Affected products (as reported)

VendorProductVersions
n/a dnsmasq dnsmasq 2.83

Weakness: CWE-358

References