Serials beginning with XAW4:
XAW4001100X and below are safe to buy
XAW4001200X and above not not safe, possibly patched
XAW4003000X and above definitely patched
Serials beginning with XAW4: XAW4001100X and below are safe to buy XAW4001200X and above not not safe, possibly patched XAW4003000X and above definitely patched