Safety and security as terms have an interesting relationship especially in Rust context - traditionally in engineering safety means defending against accidents and security means defending against malicious attackers, but "safety" in the term "memory safety" commonly implies security as well. Language is hard...
Considing whether memory leaks are a security problem brings us to the traditional CIA definition of security - the A (availability) is at risk from memory leaks.
The view of rust is rather that they’re not safety problems.
Whether they’re correctness problems is more complicated: in general they are, but there are lots of cases where they’re not, like short-running processes (once the process terminated it’s memory is reclaimed so freeing it is unnecessary overhead), or FFI (you’re moving memory out if your purview, you can’t know whether it’ll be disposed of anymore).