cassandra-rs is a Cassandra (CQL) driver for Rust. Code that attempts to use an item (e.g., a row) returned by an iterator after the iterator has advanced to the next item will be accessing freed memory and experience undefined behaviour. The problem has been fixed in version 3.0.0.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.