CVE-2021-3448

Severity: medium (CVSS 4.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-04-08 · updated 2026-06-17
Weakness: CWE-358

Description

A flaw was found in dnsmasq in versions before 2.85. When configured to use a specific server for a given network interface, dnsmasq uses a fixed port while forwarding queries. An attacker on the network, able to find the outgoing port used by dnsmasq, only needs to guess the random transmission ID to forge a reply and get it accepted by dnsmasq. This flaw makes a DNS Cache Poisoning attack much easier. The highest threat from this vulnerability is to data integrity.

Affected products

Fedoraproject Fedora: 32, 33, 34
Oracle Communications Cloud Native Core Network Function Cloud Native Environment: 1.9.0
Red Hat Enterprise Linux: 8.0
Simon Kelley dnsmasq: before 2.85 — fixed in 2.85

How to fix

Upgrade to a fixed version: Simon Kelley dnsmasq 2.85. Check the vendor advisory for mitigations.

References

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