# 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. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Not stated - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 11 Aug 2026 ## 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`). - **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 | Ecosystem | 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. ## Is RUSTSEC-2026-0254 being exploited? There is no known exploitation of RUSTSEC-2026-0254 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for RUSTSEC-2026-0254 and fix it if it is affected. What it is: RUSTSEC-2026-0254 is an use after free vulnerability in sp-sized-chunks, published on 11 Aug 2026. Exploitation: There is no known exploitation of RUSTSEC-2026-0254 in the wild and no public exploit code. Affected packages and fixed versions: - sp-sized-chunks (crates.io): affected from 0.0.0-0; no fix listed Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/RUSTSEC-2026-0254/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0254/index.md) ``` ## Sources - OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0254 --- From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0254/ Summaries are generated and may contain mistakes; the official description above is the record.