# RUSTSEC-2026-0218: `Enum` trait allows type confusion when manually implemented

> A type confusion vulnerability in the enum-map crate allows memory corruption when the Enum trait is manually implemented incorrectly.

- **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:** 21 Jul 2026

## What is RUSTSEC-2026-0218?

RUSTSEC-2026-0218 is a memory corruption vulnerability in enum-map, published on 21 Jul 2026. 

### Official description

Affected versions of this crate did not require the element type of the `Array` associated type in the `Enum` trait to match the array's generic parameter `V`.

This can result in type confusion, and consequently memory corruption, when a manual `Enum` implementation declares an `Array<V>` whose elements are not actually of type `V`:

```rust
struct IntentionallyWrong;

impl Enum for IntentionallyWrong {
    type Array<V> = [String; 4];

    fn from_usize(_: usize) -> Self {
        IntentionallyWrong
    }

    fn into_usize(self) -> usize {
        0
    }
}

enum_map! { IntentionallyWrong => 42 };
```

The flaw was corrected in commit [7a8b815432](https://codeberg.org/sugar700/enum-map/commit/7a8b8154323d426415a10accf104cd05c394cda9) by adding a `Value = V` bound to the `Array` type in the `Enum` trait.

## Which versions are affected by RUSTSEC-2026-0218?

1 open source package ship an affected version, including enum-map.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `enum-map` | crates.io | From 3.0.0-0.gat.0 | 3.1.0 |

## How do I fix RUSTSEC-2026-0218?

Upgrade enum-map to 3.1.0 or later.

## Is RUSTSEC-2026-0218 being exploited?

There is no known exploitation of RUSTSEC-2026-0218 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0218 and fix it if it is affected.

What it is: RUSTSEC-2026-0218 is a memory corruption vulnerability in enum-map, published on 21 Jul 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0218 in the wild and no public exploit code.

Affected packages and fixed versions:
- enum-map (crates.io): affected from 3.0.0-0.gat.0; fixed in 3.1.0

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-2026-0218/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0218/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0218

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0218/
Summaries are generated and may contain mistakes; the official description above is the record.