# MAL-2026-6718: Malicious code in test-pkg-yarn (npm)


- **Type:** Malicious package
- **Package:** `test-pkg-yarn` (npm)
- **Published:** 1 Jul 2026
- **Also known as:** GHSA-r653-6655-p467

## What is MAL-2026-6718?

MAL-2026-6718 is a malicious package in test-pkg-yarn, published on 1 Jul 2026. 

### Official description

package.json declares `bin: { "node": "./shim.js" }`, causing `npm`/`yarn` to symlink `node` in `node_modules/.bin` (and in a system bin dir on global install) to a package-controlled script. Subsequent invocations of `node` resolved through that PATH entry execute shim.js instead of the real Node.js runtime, redirecting any tooling that expects `node` to attacker-controlled code. In addition, `scripts.postinstall` runs `bun shim.js || node shim.js`, and shim.js unconditionally invokes OS commands at install time via `child_process.execSync` — spawning a GUI calculator (`calc` on Windows, `gnome-calculator` on Linux, `open -a Calculator` on macOS), opening a URL in the user's browser, and writing a marker file to `/tmp/.bun-npm-pwned`. The package self-identifies as 'BunnyHijack PoC - yarn variant' with the console message '[!] PATH POISONED - test-pkg-yarn just hijacked your node command.' Although framed as a proof-of-concept and not currently exfiltrating data, the behavior is real install-time code execution against any developer who installs the package and a persistent hijack of the `node` command in PATH.

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-2026-6718?

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-2026-6718 is a malicious package: test-pkg-yarn (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-2026-6718/ (Markdown: https://insights.sbomify.com/MAL-2026-6718/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6718

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-6718/
Summaries are generated and may contain mistakes; the official description above is the record.