Researchers from Tsinghua University and the University of California have identified a new method that can be used to conduct DNS cache poisoning attacks. The new discovery revives a 2008 bug that had once been thought to have resolved for good. Attackers could wreak havoc on the internet should they be able to poison DNS caches. The researchers say the new method takes advantage of a side-channel attack to deduce the source port number of the DNS cache attacks by guessing the source of the cache.
Source: https://www.bleepingcomputer.com/news/security/dns-cache-poisoning-attacks-return-due-to-linux-weakness/