yalu is a series of semi-untethered jailbreaks released for iOS. Developed by Luca Todesco (qwertyoruiop), yalu was initially released as an incomplete iOS 8.4.1 code sign and sandbox bypass, which has since been added to by others. Todesco then released a new version of yalu in beta, in the form of an IPA, supporting some devices running iOS 10.1-10.1.1. Later, another version was released supporting iOS 10.0-10.2.
The incomplete 8.4.1 yalu
Released on GitHub, yalu for 8.4.1 supports various unknown devices. Some users have managed to use the code released to achieve a fully untethered jailbreak, but nothing has been publicly released.
yalu for iOS 10.1-10.1.1
Sometimes known as YaluX or yalu + mach_portal, yalu for iOS 10.1 is currently in beta, and supports the iPad Pro, the iPhone 6s and 6s Plus, the iPhone SE and the iPhone 7 and 7 Plus, giving them a semi-untethered jailbreak. Issues have arisen with devices using TSMC manufactured chips.
When initially released, the jailbreak was intended for developers only, and users are warned about the jailbreak being unstable and buggy. Substrate is deliberately broken in an attempt to deter users from using it. However, several fixes have been made available, many resulting in issues with tweaks and forcing some users to restore.
The jailbreak utilizes several of Ian Beer's exploits discovered in the kernel of iOS 10.1.
Several beta versions have been released, with the latest, beta 4 and beta 4-1 being retracted due to bugs and errors. Beta 3 is the latest 'stable' working version.
The jailbreak is patched as of iOS 10.2, though Todesco has said he will update yalu to support iOS 10.2.
On January 25, 2017, Todesco released the incomplete source code to a new version of Yalu, one supporting every version from iOS 10.0 through 10.2, onto GitHub. On January 26, he formally released an "alpha, beta 1" version of yalu102 on his site in the form of an IPA (also sideloaded using Cydia Impactor) to jailbreak semi-untethered iOS 10.0 through 10.2. The first beta supported Cydia Substrate, and works on the iPad Pro, iPhone 6s and iPhone SE.
On January 29, yalu102 was officially updated to support all 64-bit devices on iOS 10.2, excluding the iPad Air 2, iPad mini 4, and all iPhone 7 models.
On January 30, yalu102 was officially updated to support all 64-bit devices on iOS 10.2, excluding the iPhone 7 and iPhone 7 Plus.
On February 26, yalu102 was unofficially ported to support tvOS (up to and including 10.1), as the first semi-untethered jailbreak for tvOS 10 and demonstrating the universality of the Mach voucher bug, upon which it was based. This jailbreak was released as LiberTV.
On March 27, 2017, Luca Todesco announced he was officially "done with jailbreaking" on Twitter. He has abandoned all versions of yalu. Leaving them in a theoretical "beta" state forever.