On Monday, ZecOps released a report about a couple concerning vulnerabilities with the Mail app in iOS. These vulnerabilities would allow an attacker to execute arbitrary code in the Mail app or the maild process that assists the Mail app behind the scenes. Most concerning, though, is the fact that even the most current version of iOS, 13.4.1, is vulnerable.
The way the attack works is that the threat actor sends an email message designed to cause a buffer overflow in Mail (or maild). A buffer overflow is a bug in code that allows an attack to happen if the threat actor is able to fill a block of memory beyond its capacity. Essentially, the attacker writes garbage data that fills up the memory, then writes code that overwrites existing code in adjoining memory, which later gets executed by the vulnerable process.