Systems and methods for securely sharing a memory between an Embedded Controller (EC) and a Platform Controller Hub (PCH). In some embodiments, an IHS may include: a chipset; a flash device coupled to the chipset; and an EC coupled to the flash device via a first bus and to the chipset via a second bus, wherein the EC comprises a Read-Only Memory (ROM) portion and a Random Access Memory (RAM) portion, the EC configured to: retrieve EC firmware from the flash device via the first bus; store the retrieved EC firmware in the RAM portion; and prior to the execution of any instruction stored in the RAM portion, relinquish access to the flash device via the first bus.