# RUSTSEC-2026-0128: Double-free and use-after-free in `Keys::next()`

> A double-free and use-after-free vulnerability in a Rust map library allows attackers to trigger undefined behavior and potential code execution via safe public APIs.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 May 2026

## What is RUSTSEC-2026-0128?

RUSTSEC-2026-0128 is an use after free vulnerability in emap, published on 2 May 2026. 

### Official description

`Keys::next()` uses `ptr::read` to move out the `Option<V>` by value, which
drops the contained `V` when `V` is non-Copy (e.g. `String`). This leaves a
dangling value in the map's storage slot. Subsequent `get()` operations on
that key return a dangling reference to already-freed memory.

This can be triggered through safe public APIs — `Map::keys()`,
`Keys::next()`, and `Map::get()` — with no `unsafe` required from the
caller. Under Miri, accessing the freed slot produces "Undefined Behavior:
pointer not dereferenceable: alloc has been freed, so this pointer is
dangling".

## Which versions are affected by RUSTSEC-2026-0128?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `emap` | crates.io | From 0.0.0-0 | None |

## How do I fix RUSTSEC-2026-0128?

No fix has been published for RUSTSEC-2026-0128 yet. Limit exposure of the affected software until one is available.

## Is RUSTSEC-2026-0128 being exploited?

There is no known exploitation of RUSTSEC-2026-0128 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0128 and fix it if it is affected.

What it is: RUSTSEC-2026-0128 is an use after free vulnerability in emap, published on 2 May 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0128 in the wild and no public exploit code.

Affected packages and fixed versions:
- emap (crates.io): affected from 0.0.0-0; no fix listed

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-2026-0128/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0128/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0128

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0128/
Summaries are generated and may contain mistakes; the official description above is the record.