GMS-2022-27: Unchecked validity of Facing values in PlayerActionPacket

Impact

A remote attacker may crash a server by sending PlayerActionPacket with invalid facing values (e.g. negative), specifically with START_BREAK or CRACK_BLOCK actions, or with a UseItemTransactionData (typically in InventoryTransactionPacket).

Patches

f126479c37ff00a717a828f5271cf8e821d12d6c

Workarounds

Using a plugin, cancel DataPacketReceiveEvent if the packet is PlayerActionPacket and the facing is outside the range 0-5 when receiving START_BREAK or CRACK_BLOCK actions, or UseItemTransactionData. However, beware that negative values may be legitimate in some cases.

For more information

If you have any questions or comments about this advisory:

• Email us at team@pmmp.io