crossbeam-deque is a package of work-stealing deques for building task schedulers when programming in Rust. In versions prior to 0.7.4 and 0.8.0, the result of the race condition is that one or more tasks in the worker queue can be popped twice instead of other tasks that are forgotten and never popped. If tasks are allocated on the heap, this can cause double free and a memory leak. If not, this still can cause a logical bug. Crates using `Stealer::steal`, `Stealer::steal_batch`, or `Stealer::steal_batch_and_pop` are affected by this issue. This has been fixed in crossbeam-deque 0.8.1 and 0.7.4.

Crossbeam is a set of tools for concurrent programming. In crossbeam-channel before version 0.4.4, the bounded channel incorrectly assumes that `Vec::from_iter` has allocated capacity that same as the number of iterator elements. `Vec::from_iter` does not actually guarantee that and may allocate extra memory. The destructor of the `bounded` channel reconstructs `Vec` from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when `Vec::from_iter` has allocated different sizes with the number of iterator elements. This has been fixed in crossbeam-channel 0.4.4.

An issue was discovered in the crossbeam crate before 0.4.1 for Rust. There is a double free because of destructor mishandling.