open-vm-tools contains tools for VMware guests.
A pipe accessible to unprivileged users in the VMWare guest does not sufficiently sanitize input.
An unprivileged guest user could achieve root privileges within the guest.
There is no known workaround at this time.
All open-vm-tools users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-emulation/open-vm-tools-12.1.0"