Hackers linked to the Anonymous collective have posted stolen VMware source code prompting the company to advise customers apply patches.
VMWare platform security director Iain Mulholland confirmed the dump contained VMware ESX source code from 2004 which was linked to a leak in April this year.
"It is possible that more related files will be posted in the future," Mulholland said.
"We take customer security seriously and have engaged our VMware Security Response Centre to thoroughly investigate."
Mulholland said customers would be protected by applying product updates and patches.
The hacker dumped the code via Bit Torrent.
"It is the VMkernel from between 1998 and 2004, but as we all know, kernels don't change that much in programs, they get extended or adapted but some core functionality still stays the same," the hacker wrote in text accompanying the dump.
Purported Organization for Security and Cooperation in Europe (OCSE) documents were also dumped during the protests linked to Guy Fawkes day.
Anonymous said the dump was made to draw attention to alleged falsifications in election results in the Ukraine last week.
In further attacks, hackers linked to the anti-security (AntiSec) movement claimed they possessed data from intelligence company Stratfor, credit card details from "US officers", and a list of allegedly compromised emails from Colombian prisons.
It also dumped what it claimed was 28,000 hacked PayPal accounts complete with names, email addresses and passwords. The company said it had not found evidence to validate the claims.
The Anonymous Australia group meanwhile said the collective had defaced a series of Australian websites -- including a Government organisation dedicated to people with disabilities -- with text deriding the Federal Government's proposed data retention laws.
With Darren Pauli.