Dnsmasq: DNS cache poisoning — GLSA 202105-20

Use of insufficient randomness in Dnsmasq might lead to DNS Cache Poisoning.

Affected packages

Package	net-dns/dnsmasq on all architectures
Affected versions	< 2.85
Unaffected versions	>= 2.85

Background

Dnsmasq is a lightweight and easily-configurable DNS forwarder and DHCP server.

Description

It was discovered that Dnsmasq, when configured with --server=<address>@ or similar (e.g. through dbus), configured a fixed UDP port for all outgoing queries to the specified upstream DNS server.

Impact

An attacker, by sending malicious crafted DNS responses, could perform a DNS Cache Poisoning attack.

Workaround

There is no known workaround at this time.

Resolution

All Dnsmasq users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-dns/dnsmasq-2.85"

References

CVE-2021-3448

Release date
May 26, 2021

Latest revision
May 26, 2021: 1

Severity
low

Exploitable
local, remote

Bugzilla entries

782130