MAL-2026-6221 Malicious code in chai-assert-kit (npm)

Malicious package Published
Package
chai-assert-kit
Registry
npm

What is MAL-2026-6221?

MAL-2026-6221 is a malicious package in chai-assert-kit, published on 19 Jun 2026.

Official description

Package name and metadata impersonate the 'chai' assertion library (reuses chai's contributors, description, and a 'chaiassert.com' homepage), but the package contains no assertion logic. On require()/import, index.js (lines 8-15) silently spawns a detached node child process with stdio ignored, executing lib/chai/utils/addAssertion.js. That file is a heavily obfuscated obfuscator.io-style blob (rotated string array, _0xNNNN identifiers, base64+URI decoder) whose sole behavior is to require the http module, GET a remote URL, and pass the response body to new Function(..., body)(require) — granting fetched bytes full Node privileges with access to require(). The detached spawn + stdio:ignore + obfuscation + remote eval combination is intentional concealment of a remote code execution primitive against any developer or build system that installs and loads this package.

What should I do about MAL-2026-6221?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

Sources

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