VMware has released a Fusion 6 upgrade, offering Mavericks compatibility and Windows 8.1 VM support.

VMware Fusion v4 and older will not run reliably with Mavericks. VMware Fusion v5 patched to the latest version has been confirmed to run under Mavericks, with several glitches including: Multiple display full screen problems, DNS resolution issues if the VM is run in NAT mode, and the inability to use more than one processor core.