For that there is bytecode verification as intermediate step, and if you want to go crazy with security, hardware memory tagging with capabilities.

Which at this point most companies would rather save money and forbid JIT altogether.

Note that mainframes and micros have JIT environments that aren't at the same safety level as regular desktop PCs.

For example,

https://medium.com/@dhemanthc/ibm-i-architecture-how-timi-an...