Comment by odo1242
16 hours ago
iMessage's attachment renderer is also sandboxed, actually. You might be talking about this vulnerability: https://projectzero.google/2021/12/a-deep-dive-into-nso-zero..., but the second half of the vulnerability exploit chain was finding a way out of the CoreGraphics (Apple's image rendering library) sandbox to hack the rest of the system.
Yes, I think that was it, thanks!