Your submission was sent successfully! Close

USN-4976-1: Dnsmasq vulnerability

2 June 2021

Dnsmasq could be exposed to cache poisoning.



  • dnsmasq - Small caching DNS proxy and DHCP/TFTP server


Petr Mensik discovered that Dnsmasq incorrectly randomized source ports in
certain configurations. A remote attacker could possibly use this issue to
facilitate DNS cache poisoning attacks.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 21.04
Ubuntu 20.10
Ubuntu 20.04
Ubuntu 18.04

After a standard system update you need to reboot your computer to make
all the necessary changes.


Related notices

  • USN-4976-2: dnsmasq-base, dnsmasq-utils, dnsmasq, dnsmasq-base-lua