RUSTSEC-2026-0254 Panic-safety unsoundness in `Chunk` and `InlineArray` (use-after-free / double-free)
A use-after-free and double-free vulnerability in sp-sized-chunks allows attackers to cause memory corruption or crashes via safe Rust code if element drops panic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- None listed
What is RUSTSEC-2026-0254?
RUSTSEC-2026-0254 is an use after free vulnerability in sp-sized-chunks, published on 11 Aug 2026.
Official description
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.
Which versions are affected by RUSTSEC-2026-0254?
1 open source package ship an affected version, including sp-sized-chunks.
| Package | Affected | Fixed in |
|---|---|---|
sp-sized-chunks crates.io | From 0.0.0-0 | None |
How do I fix RUSTSEC-2026-0254?
No fix has been published for RUSTSEC-2026-0254 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is RUSTSEC-2026-0254 being exploited?
There is no known exploitation of RUSTSEC-2026-0254 in the wild and no public exploit code.