Security research firm Calif disclosed the first publicly documented macOS kernel memory corruption exploit on Apple's M5 silicon , the first to bypass Memory Integrity Enforcement, the hardware-assisted memory safety system Apple introduced as the marquee security feature of its M5 and A19 chips. The exploit chain was built in five days by Calif researchers working in collaboration with Anthropic's Mythos Preview model, and was disclosed in person to Apple at the company's Cupertino headquarters rather than through the standard submission queue. The vulnerability is a data-only kernel local privilege escalation chain targeting macOS 26.4.1 on bare-metal M5 hardware with kernel MIE enabled. It begins from an unprivileged local user, uses only normal system calls, and ends with a root shell.