# MAL-2026-3751: Malicious code in cache-poisoning-pwn-demo (npm)


- **Type:** Malicious package
- **Package:** `cache-poisoning-pwn-demo` (npm)
- **Published:** 14 May 2026

## What is MAL-2026-3751?

MAL-2026-3751 is a malicious package in cache-poisoning-pwn-demo, published on 14 May 2026. 

### Official description

The package's postinstall hook (`node -e "try { require('./dist/postinstall.js'); } catch(e) {}"`) loads dist/postinstall.js, which bundles a poisoned is-number module whose top-level IIFE unconditionally calls `child_process.exec` with a platform-specific command: `open -a Calculator` on macOS, `calc.exe` on Windows, `gnome-calculator`/`xcalc` on Linux. The same IIFE is also present in dist/index.js (the package's `main` entry), so any consumer that does `require('cache-poisoning-pwn-demo')` or `import`s it will also spawn a child process with no user consent. The package self-describes as a supply-chain attack demonstration. While today's payload spawns only a calculator, the mechanism is a fully functional install-time and import-time arbitrary-command executor: any installer running `npm install` or any downstream library that transitively requires this package will execute the hardcoded command in the installer's context. The calculator is a demonstration payload; the delivery primitive is a real attack.

## What should I do about MAL-2026-3751?

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-2026-3751 is a malicious package: cache-poisoning-pwn-demo (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-2026-3751/ (Markdown: https://insights.sbomify.com/MAL-2026-3751/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-3751

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-3751/
Summaries are generated and may contain mistakes; the official description above is the record.