# MAL-2026-6523: Malicious code in express-plugin (npm)


- **Type:** Malicious package
- **Package:** `express-plugin` (npm)
- **Published:** 26 Jun 2026

## What is MAL-2026-6523?

MAL-2026-6523 is a malicious package in express-plugin, published on 26 Jun 2026. 

### Official description

On module load, index.js auto-invokes initPlugin(), which HTTP-GETs https://jsonkeeper.com/b/PRA3O, parses the JSON response, and passes the response's `cookie` field to `Function.constructor` with `require` exposed, then immediately invokes the resulting function. Any process that does `require('express-plugin')` executes arbitrary JavaScript pulled from a mutable third-party paste host with full Node `require` privileges, giving the operator of that paste full control of the installer's machine. The file is headed as `normalize-path (ES6 safe version)` and exports an unused normalizePath function as decoy; the package name `express-plugin` is cover framing intended to make the package look like a benign Express middleware. The remote payload is attacker-mutable: today's content can be swapped for credential theft, persistence, or any other action at any time without republishing the package.

## What should I do about MAL-2026-6523?

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-2026-6523 is a malicious package: express-plugin (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-2026-6523/ (Markdown: https://insights.sbomify.com/MAL-2026-6523/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6523

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6523/
Summaries are generated and may contain mistakes; the official description above is the record.