---
id: RUSTSEC-2026-0218
title: '`Enum` trait allows type confusion when manually implemented'
summary: '`Enum` trait allows type confusion when manually implemented'
severity: none
vendor: enum-map
product: enum-map
ecosystem: rust
affected:
  - 'enum-map >= 3.0.0-0.gat.0, < 3.1.0'
patched:
  - enum-map 3.1.0
published: '2026-07-21'
updated: '2026-07-28'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/RUSTSEC-2026-0218'
references:
  - url: 'https://crates.io/crates/enum-map'
  - url: 'https://rustsec.org/advisories/RUSTSEC-2026-0218.html'
  - url: >-
      https://codeberg.org/sugar700/enum-map/src/branch/master/CHANGELOG.md#version-310
  - url: 'https://github.com/rustsec/advisory-db/issues/3060'
tags:
  - osv
  - rust
ingestedAt: '2026-07-29T19:09:38.031Z'
---

## Overview

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.

## Affected packages

- `enum-map >= 3.0.0-0.gat.0, < 3.1.0`

## Remediation

Upgrade to a patched release:

- `enum-map 3.1.0`