MAL-2026-12501 Malicious code in william-data-formatter-x (npm)
Malicious package
Published
MAL-2026-12501 is a malicious package: william-data-formatter-x (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-2026-12501/ (Markdown: https://insights.sbomify.com/MAL-2026-12501/index.md)
- Package
- william-data-formatter-x
- Registry
- npm
What is MAL-2026-12501?
MAL-2026-12501 is a malicious package in william-data-formatter-x, published on 5 Aug 2026.
Official description
The package declares a preinstall script (node index.js) that, on Windows, spawns a hidden PowerShell window (-WindowStyle Hidden) to fetch https://files.catbox.moe/5khq55.zip, extract it to %TEMP%, and execute Verification_Tool.exe. The fetched binary is unpinned, unhashed, and hosted on an anonymous file-drop service unrelated to the package's stated purpose. The package name has a leading space (' william-data-formatter-x') and carries generic 'Internal sync utility' / 'IT Operations' metadata consistent with social-engineering framing. Installing this package on a Windows machine results in arbitrary attacker-controlled code executing on the installer's host at npm install time.
What should I do about MAL-2026-12501?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.