RUSTSEC-2021-0050: swap_index can write out of bounds and return uninitialized memory

What to do

1. See which version you have: cargo tree -i reorder (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p reorder. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example reorder = "1.1.0") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

swap_index takes an iterator and swaps the items with their corresponding indexes. It reserves capacity and sets the length of the vector based on the .len() method of the iterator.

If the len() returned by the iterator is larger than the actual number of elements yielded, then swap_index creates a vector containing uninitialized members. If the len() returned by the iterator is smaller than the actual number of members yielded, then swap_index can write out of bounds past its allocated vector.

As noted by the Rust documentation, len() and size_hint() are primarily meant for optimization and incorrect values from their implementations should not lead to memory safety violations.

Patch

A new version crate was pushed that marks this function as unsafe.

reorder = "1.1.0"

Previous versions have also been yanked from crates.io.

References

• Package: crates.io/crates/reorder
• Advisory: rustsec.org/advisories/RUSTSEC-2021-0050.html
• Report: github.com/tiby312/reorder/issues/1

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.