Stolen VMware source code will be unveiled on Saturday 5 May by hacker "Hardcore Charlie", who claims that he downloaded the code from the cracked systems of companies in the Far East.
The hacker has already released a "sneak preview" of the 300MB that he claims to have in his possession. The source code dates back as far as 2003 and 2004.
The virtualisation software vendor has long been plagued by claims that its software platform is insecure. A 2010 study by computer giant IBM, for example, suggested that as many as one-third of the security flaws in virtualised environments could be traced back to VMware's Hypervisor platform.
The security breach was confirmed by Iain Mulholland, director of the VMware Security Response Center, who attempted to downplay the significance of the issue in a blog posting.
"The fact that the source code may have been publicly shared does not necessarily mean that there is any increased risk to VMware customers. VMware proactively shares its source code and interfaces with other industry participants to enable the broad virtualisation ecosystem today," wrote Mulholland.
However, he admitted that the company is investigating the breach.
"We take customer security seriously and have engaged internal and external resources, including our VMware Security Response Center, to thoroughly investigate. We will continue to provide updates to the VMware community if and when additional information is available."
In 2008, the company opened up Hypervisor to security software vendors by producing a set of APIs, called VMsafe, to enable them to extend their protection to virtual machines against keyloggers, viruses, Trojans and other malware.