VMware vCenter Server (6.5 prior to 6.5 U1) contains an information disclosure vulnerability. This issue may allow plaintext credentials to be obtained when using the vCenter Server Appliance file-based backup feature.
VMware vCenter Server 5.5, 6.0, 6.5 allows vSphere users with certain, limited vSphere privileges to use the VIX API to access Guest Operating Systems without the need to authenticate.