# RUSTSEC-2026-0298: Use-after-free when a future's `Drop` panics while the container is dropped

> A use-after-free vulnerability in the Storage component allows attackers to cause memory corruption or crashes when a future's Drop implementation panics during container cleanup.

- **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:** 12 Sep 2026
- **Also known as:** GHSA-8gw6-724c-9h38

## What is RUSTSEC-2026-0298?

RUSTSEC-2026-0298 is an use after free vulnerability in unicycle, published on 12 Sep 2026. 

### Official description

`Storage::clear` walks the slab, empties each entry and frees the `Task`
allocation once its reference count reaches zero. `self.tasks.set_len(0)` only
runs after the loop.

Emptying an entry drops the user future it holds, and `T` carries no bounds
excluding a panicking `Drop`. If one unwinds, the length is never committed and
`self.tasks` still holds the pointers already processed. `Drop for Storage`
calls `clear` again, and the second pass dereferences `(*task.as_ptr()).entry`
on allocations the first pass already freed — a use-after-free (CWE-416)
reachable from safe Rust.

`Storage` is reached only through `Unordered`, whose `Drop` calls `clear`. No
particular method call is needed; dropping the container is enough.

## Mitigation

Update to 0.10.3.

## Which versions are affected by RUSTSEC-2026-0298?

1 open source package ship an affected version, including unicycle.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `unicycle` | crates.io | From 0.0.0-0 | 0.10.3 |

## How do I fix RUSTSEC-2026-0298?

Upgrade unicycle to 0.10.3 or later.

## Is RUSTSEC-2026-0298 being exploited?

There is no known exploitation of RUSTSEC-2026-0298 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0298 and fix it if it is affected.

What it is: RUSTSEC-2026-0298 is an use after free vulnerability in unicycle, published on 12 Sep 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0298 in the wild and no public exploit code.

Affected packages and fixed versions:
- unicycle (crates.io): affected from 0.0.0-0; fixed in 0.10.3

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-2026-0298/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0298/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0298

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0298/
Summaries are generated and may contain mistakes; the official description above is the record.