RUSTSEC-2022-0010: enum_map macro can cause UB when `Enum` trait is incorrectly implemented

What to do

1. See which version you have: cargo tree -i enum-map (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p enum-map. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example enum-map = "2.0.2") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

Affected versions of this crate did not properly check the length of an enum when using enum_map! macro, trusting user-provided length.

When the LENGTH in the Enum trait does not match the array length in the EnumArray trait, this can result in the initialization of the enum map with uninitialized types, which in turn can allow an attacker to execute arbitrary code.

This problem can only occur with a manual implementation of the Enum trait, it will never occur for enums that use #[derive(Enum)].

Example code that triggers this vulnerability looks like this:

enum E {
    A,
    B,
    C,
}

impl Enum for E {
    const LENGTH: usize = 2;

    fn from_usize(value: usize) -> E {
        match value {
            0 => E::A,
            1 => E::B,
            2 => E::C,
            _ => unimplemented!(),
        }
    }

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

impl<V> EnumArray<V> for E {
    type Array = [V; 3];
}

let _map: EnumMap<E, String> = enum_map! { _ => "Hello, world!".into() };

The flaw was corrected in commit b824e23 by putting LENGTH property on sealed trait for macro to read.

References

• Package: crates.io/crates/enum-map
• Advisory: rustsec.org/advisories/RUSTSEC-2022-0010.html
• Web: gitlab.com/KonradBorowski/enum-map/-/blob/master/CHANGELOG.md#version-202

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for enum-map

• UnsoundRUSTSEC-2026-0218 · 2026-07-21`Enum` trait allows type confusion when manually implemented

Full security history of enum-map