macOS FileVault2 let attackers with physical access retrieve the password in clear text by plugging in a $300 Thunderbolt device into a locked or sleeping mac. The password may be used to unlock the mac to access everything on it. To secure your mac just update it with the December 2016 patches.Anyone including, but not limited to, your colleagues, the police, the evil maid and the thief will have full access to your data as long as they can gain physical access – unless the mac is completely shut down. If the mac is sleeping it is still vulnerable.Just stroll up to a locked mac, plug in the Thunderbolt device, force a reboot (ctrl+cmd+power) and wait for the password to be displayed in less than 30 seconds!

Source: Security | DMA | Hacking: macOS FileVault2 Password Retrieval