[cesarb]

The difference is that on Rust the [] operator does bounds checking: it'll reliably panic before accessing memory if the index is out of bounds. While on C++, the [] operator will happily let the program read or write outside the array bounds.

Depending on compile-time options, a Rust panic can either cause an immediate crash, or do something similar to throwing a C++ exception, complete with stack unwinding.

[Manishearth]

Yeah, and because it's reliable, you don't need to worry about security issues -- the worst this can do is abort the application.

Whereas for this bug it's quite possible that it may be exploitable. Especially given that the crash backtrace doesn't always appear in the same place -- something is corrupting memory that gets discovered later. (This explains why I can sometimes get the string to render for a split second before crashing)