MAL-2026-13940 Malicious code in @opezneppelin/contracts (npm)
Malicious package
Published
MAL-2026-13940 is a malicious package: @opezneppelin/contracts (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-2026-13940/ (Markdown: https://insights.sbomify.com/MAL-2026-13940/index.md)
- Package
- @opezneppelin/contracts
- Registry
- npm
What is MAL-2026-13940?
MAL-2026-13940 is a malicious package in @opezneppelin/contracts, published on 13 Aug 2026.
Official description
@opezneppelin/contracts is a typosquat of @openzeppelin/contracts. Its postinstall lifecycle script (scripts/postinstall.js) hex-escapes all module names, method names, and string constants (fs, https, child_process, powershell, -NoP,.exe) and stores the download URL as a base64 literal that decodes to https://files.catbox.moe/9bppy2.zip. On Windows installers, the script downloads that ZIP to %TEMP%, expands it via PowerShell Expand-Archive, recursively searches the extracted contents for the first.exe, and spawns it detached. The destination is an anonymous, mutable file-host (catbox.moe) unrelated to any OpenZeppelin infrastructure, and the fetched executable is opaque attacker-controlled content. The behavior fires automatically on npm install without any user action, resulting in arbitrary code execution on the installer's Windows host.
What should I do about MAL-2026-13940?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.