Is there a safety issue with halogen bulbs if the outer glass envelope comes off leaving exposed wires
Yes, there are safety issues.

Firstly those wires are connected to the cap of the bulb which will be connected to the mains.

Secondly the outer cover acts as a UV filter, so if the halogen bulb is still working but the outer cover has come off the bulb will produce high levels of UV which are bad for your eyes.

You should treat the bulb the same as you would treat a conventional incandescent bulb whose glass envelope has broken or fallen off. Isolate the circuit (do not rely on lightswitches for safety isolation) and then carefully remove the bulb.