If you have not patched your esx/esxi, do it!

when?

NOW

Patch overview : http://www.vmware.com/security/advisories/VMSA-2011-0007.html

ESX3.5 and  ESX3.03 are safe.

Patch can be obtained here: (ESXi410-201104001 )

http://www.vmware.com/patch/download/

Unzip it and copy  files to your esxi box(you should have embeddedEsx directory after unpacking)

issue command:

esxupdate -m metadata.zip update

Make sure that host is in Maintenance  mode, and machines are powered off, or migrated to other host in cluster  if you have one. After installing all patches reboot your host.

After reboot check if patches were installed by typing:

esxupdate query

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_esxupdate.pdf -> you can read vmware manual regarding updating your host

http://www.vmware.com/support/developer/vcli/vcli41/doc/reference/vihostupdate.html -> here is short manual for vihostupdate if you want to upgrade it using rcli like vMA