It seems to me that this exploit was used in a chain with a WhatsApp issue that would trigger the malicious DNG data to be loaded as a zero click, presumably just into WhatsApp. It’s unclear to me if there was a sandbox escape or kernel vulnerability used along with this; it might have been used to exfiltrate WhatsApp messages only.
This would explain why there’s only a single patch for a simple memory corruption issue; usually an attacker would need a lot of chained vulnerabilities to bypass mitigations on iOS, but if the vulnerability is in the exact target application to begin with, it sure does make things easier.
