CVE-2020-35927: Data races in thex

The core vulnerability stems from the improper Sync trait implementation for Thex<T>. In Rust, Sync indicates a type can be safely shared between threads via references. However, the implementation lacked a T: Send bound, violating Rust's safety guarantees. This allows Thex<T> to be marked as thread-safe (Sync) even when containing non-Send types like Rc, enabling cross-thread data races. The advisory explicitly identifies this missing bound as the root cause, making the Sync trait implementation the clear vulnerable component.