Hackers can use Windows virtual machines to attack other systems.

Virtualization software VMware Fusion has a serious security vulnerability that hackers can use to execute malicious code on another operating system through a Windows virtual machine.

Security agency Immunity said that a critical vulnerability in VMware's virtual machine display capabilities could be used to read and write to memory on the host operating system.

Immunity did a demonstration of exploiting the vulnerability to attack a host system in a demo environment where the host is running Vista SP1 and the virtual machine is running Windows XP. Immunity said that it is also very easy to perform this vulnerability on Mac or Linux machines.

Currently, VMware claims to have fixed the vulnerability.