mast1c0re (pronounced as masticore) is the name of a vulnerability in PS4's PS2 emulator that allows sideloading/swapping PS2 game ISOs. It also provides the necessary framework for developing payloads that can be executed on the PlayStation 4 or PlayStation 5 through a PlayStation 2 game save file by escaping the PlayStation 2 emulator. A more maintained fork of mast1c0re is also available from EchoStretch.
Mast1c0re has also been implemented to use the Lapse kernel exploit with laps3c0re, which allows it to additionally act as a jailbreak method. A guide on using Lapsecore can be found here.
Advantages of Mast1c0re compared to building PS2toPS4 FPKGs
- Works on all firmwares, even non-exploitable firmwares, including the latest firmware.
- Doesn't require creating FPKGs; can load PS2 ISOs locally from a USB drive or remotely via network share from a PC.
- Is a userland exploit and has the ability to enable some homebrew, such as an FTP server.
- Supports custom game configs.
Disadvantages of Mast1c0re compared to building PS2toPS4 FPKGs
- Requires owning Okage: Shadow King from PSN.
- Swapped ISOs are not persistent after the game is closed. Saves, however, will remain.
- Requires the exploited game save to be resigned, meaning for firmwares higher than 13.00, Save Wizard may be required.
- PS2 emulation on exploited PS4s requires both choosing a specific emulator base (from different PS2 Classics games released by Sony on PSN) and custom configs. mast1c0re only supports Okage: Shadow King, meaning that is the only emulator base it can use. As a result, compatibility will be lowered overall.