What exactly do you mean? If you ask C/C++ programmers, what they don't like about C/C++ and fix that, you got Rust. C++ wants to stay backwards compatible, which is holding the language back. Rust was a fresh start.
What I mean is that Rust brings the ownership tracking of memory as a primary concept. With C++ that's more of an add-on. I should add that I'm an old time C++er and don't have Rust hands-on experience
I consider C/C++ not having ownership of memory as a primary concept to be one of its ugliness's.