RUSTSEC-2026-0255: Panic-safety unsoundness in `Chunk`, `RingBuffer`, and `InlineArray` (use-after-free / double-free)

What to do

1. Find who pulls it in: cargo tree -i sized-chunks.
2. Avoid the affected API (sized_chunks::Chunk::clear, sized_chunks::Chunk::drop_left, sized_chunks::Chunk::drop_right, sized_chunks::InlineArray::clear, sized_chunks::RingBuffer::clear, sized_chunks::RingBuffer::drop_left), or replace the crate.

Details from the advisory

Several methods in sized-chunks drop elements before updating the 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's own Drop runs, those elements are visited again , a use-after-free / double-free reachable from safe Rust.

The RingBuffer methods require the ringbuffer feature. This is distinct from RUSTSEC-2020-0041 (Chunk::clone / insert_from, fixed in 0.6.3); the methods here are still affected in 0.7.0. The repository is archived with issues/PRs disabled and no fix available.

Impact

• **CWE-415 (Double Free):** the same allocation is freed twice.
• **CWE-416 (Use-After-Free):** a freed allocation is accessed during a repeated Drop.

Reachable entirely from safe Rust via catch_unwind with element types whose Drop can panic.

References

• Package: crates.io/crates/sized-chunks
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0255.html

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

Other advisories for sized-chunks

• Vulnerability HighRUSTSEC-2020-0041 · 2020-09-06Multiple soundness issues in Chunk and InlineArray
• UnmaintainedRUSTSEC-2026-0251 · 2026-05-03sized-chunks is unmaintained

Full security history of sized-chunks