# RUSTSEC-2026-0292: Double free / use-after-free in `Chunk` and `InlineArray` removal methods when an element's `Drop` panics

> A double free or use-after-free vulnerability in Rust collection libraries allows attackers to cause crashes or potentially execute code if element drop panics.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026

## What is RUSTSEC-2026-0292?

RUSTSEC-2026-0292 is an use after free vulnerability in imbl-sized-chunks, published on 4 Sep 2026. 

### Official description

`Chunk::{clear, drop_left, drop_right}` and `InlineArray::{clear, truncate}` drop the removed elements before updating the metadata that records which slots hold live values — the `left`/`right` index pair for `Chunk`, the length field for `InlineArray`. If an element's `Drop` panics during the drop, that update is never reached, so the collection still treats the already-dropped elements as live. When the collection is later dropped (its destructor walks the range described by the stale metadata), or a subsequent operation touches the same slots, those elements are dropped a second time — a double free (CWE-415) / use-after-free (CWE-416) reachable from safe Rust.

The stale field is `left` and `right` for `Chunk::clear`, `left` for `drop_left`, `right` for `drop_right`, and the length field for both `InlineArray` methods.

## Mitigation

Upgrade to `imbl-sized-chunks` 0.2.0 or later, which commits the metadata before dropping any element (fixed in jneem/imbl-sized-chunks#14, released in 0.2.0).

## Which versions are affected by RUSTSEC-2026-0292?

1 open source package ship an affected version, including imbl-sized-chunks.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `imbl-sized-chunks` | crates.io | From 0.0.0-0 | 0.2.0 |

## How do I fix RUSTSEC-2026-0292?

Upgrade imbl-sized-chunks to 0.2.0 or later.

## Is RUSTSEC-2026-0292 being exploited?

There is no known exploitation of RUSTSEC-2026-0292 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0292 and fix it if it is affected.

What it is: RUSTSEC-2026-0292 is an use after free vulnerability in imbl-sized-chunks, published on 4 Sep 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0292 in the wild and no public exploit code.

Affected packages and fixed versions:
- imbl-sized-chunks (crates.io): affected from 0.0.0-0; fixed in 0.2.0

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-2026-0292/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0292/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0292

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0292/
Summaries are generated and may contain mistakes; the official description above is the record.