RUSTSEC-2026-0254

Several methods in `sp-sized-chunks` drop elements before updating the container's length/boundary metadata. If an element's `Drop` panics during the drop, the metadata update is skipped, so the container still treats the already-dropped elements as live. When the container is later dropped, its own `Drop` re-visits those slots and drops the freed elements again — a use-after-free / double-free reachable from safe Rust.

`sp-sized-chunks` is a fork of `sized-chunks` (companion advisory filed separately) and carries the same bug. The repository is archived and the crate is still on 0.1.0 with no fix available.

## Impact

- **CWE-415 (Double Free):** the same allocation is freed twice (e.g. an element holding `Box<T>`). - **CWE-416 (Use-After-Free):** an element reads its own freed allocation during `Drop` (e.g. `String`) — confirmed under AddressSanitizer.

All are reachable from safe Rust via `catch_unwind` with element types whose `Drop` can panic.