Chinese security researchers discovered that the firmware of fast chargers can be corrupted to deliver higher charging parameters, thus damaging the devices connected to them. A charger affected by a BadPower attack can melt or even set on fire the handset/external battery it is supposed to charge.
https://www.notebookcheck.net/BadPower-can-melt-or-set-your-phone-on-fire.482336.0.html