# RUSTSEC-2026-0205: `Array::insert` violates exception safety if compare function panics, leading to potential Double-Free

> A Rust library's Array::insert method causes a double-free if the user-provided comparison function panics, potentially allowing code execution or crashes.

- **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:** 6 Jul 2026

## What is RUSTSEC-2026-0205?

RUSTSEC-2026-0205 is an use after free vulnerability in scc, published on 6 Jul 2026. 

### Official description

In affected versions of this crate, `Array::insert` is not exception safe. In the `UPSERT` path, `key` and `value`'s snapshot is written to `self.data_block`, and after the insertion is completed, `key` and `value` are `mem::forget` in order to prevent double free. However, during the insertion, `K::compare` is invoked, which is a user-provided method. If user deliberately call panic in this function, during unwinding, the destructors of `key`, `value`, and `self` will all be called (since the `mem::forget` has not been called yet), leading to Double Free. Similar issues happens in the `!UPSERT` path.

The soundness issue was fixed in version `3.8.4` by using `ManuallyDrop` instead of `mem::forget`, and separating fallible code from infallible code during a node split - insert = insert_try -> insert_unchecked.

## Which versions are affected by RUSTSEC-2026-0205?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `scc` | crates.io | From 0.0.0-0 | 3.8.4 |

## How do I fix RUSTSEC-2026-0205?

Upgrade scc to 3.8.4 or later.

## Is RUSTSEC-2026-0205 being exploited?

There is no known exploitation of RUSTSEC-2026-0205 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0205 and fix it if it is affected.

What it is: RUSTSEC-2026-0205 is an use after free vulnerability in scc, published on 6 Jul 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0205 in the wild and no public exploit code.

Affected packages and fixed versions:
- scc (crates.io): affected from 0.0.0-0; fixed in 3.8.4

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-2026-0205/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0205/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0205

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0205/
Summaries are generated and may contain mistakes; the official description above is the record.