Fugu was an open-sourced semi-tethered jailbreak, developed by Linus Henze, based on checkm8. Fugu was the first jailbreak of its kind to utilize the newfound BootROM exploit while staying open sourced. The jailbreak has support for the A10 Fusion and A10X Fusion SOCs on the iPhone 7, iPad Pro (12.9-inch) (2nd generation), and iPad Pro (10.5-inch) on iOS versions 13.0-13.5.1. Fugu was officially archived on Linus' GitHub page on October 3, 2023.

Fugu consists of 4 main components to make it run successfully: Fugu, the iStrap Loader, iStrap, and iDownload. Fugu is the macOS application itself, while iStrap and iStrap Loader are internal components that make various patches to the device. The iStrap Loader uses shellcode to patch iBoot on the device. Once this is done, the loader will call iStrap, which is the kernel bootstrapper. iStrap can inject boot arguments that are requested by the end user, but it is not required by default. iDownload is an on-device application that is installed and ran during boot instead of launchd. It works by forking itself over to launchd.

• On the projects official GitHub page, there is precompiled builds of Fugu that can be downloaded in the release section. However, a user can also build it themselves using Xcode and Homebrew (*MacOS only*). llvm and binutils are required to be installed with Homebrew.

• To jailbreak a device that is compatible, a user should run Fugu iStrap. Launching Fugu with no parameters will display additional options.