> An application that has permission to map memory pages as executable is a coveted target for spyware and malware as it provides a much better starting point f

> An application that has permission to map memory pages as executable is a coveted target for spyware and malware as it provides a much better starting point for pivoting to root and pwning the entire OS No more than any other app. It runs anyway in the app sandbox, and can only access the resources that are accessible from the app sandbox itself. For the application to gain root privileges it would need to exploit a flaw in the sandbox itself, something difficult these days. Android allows applications to map memory pages as executable (in fact you can also launch any Linux executable as a subprocess) and there was never an issue about security: if you don't have a rooted phone you don't have chances to get code running as root, since everything runs in the app container. And if there is a flaw that allows escaping from the app sandbox, it can probably be exploited without being able to map memory pages as executable anyway, since it will probably be a flaw in a kernel system call or library function. So really: this was always a limitation that Apple did impose to not allow in practice competing browsers in the Apple store, since a browser to be efficient this day needs to compile code as JIT, as well as not allowing applications that benefit for JIT execution (such as emulators or compilers).