CVE-2021-28032: Use after free in nano_arena

Severity: Critical

CVSS Score: 9.8

An issue was discovered in the nano_arena crate before 0.5.2 for Rust. There is an aliasing violation in split_at because two mutable references can exist for the same element, if Borrow<Idx> behaves in certain ways. This can have a resultant out-of-bounds write or use-after-free.