# MAL-2026-6440: Malicious code in tokenization-util (npm)


- **Type:** Malicious package
- **Package:** `tokenization-util` (npm)
- **Published:** 25 Jun 2026
- **Also known as:** GHSA-wp9r-fqrq-cg5h

## What is MAL-2026-6440?

MAL-2026-6440 is a malicious package in tokenization-util, published on 25 Jun 2026. 

### Official description

The package advertises plain math/formatter helpers but index.js contains a heavily obfuscated payload concealed inside the calculateTokenPrice function. The payload is hidden behind ~1500 leading tab characters of visual padding, then uses two seeded Fisher-Yates string-shuffler decoders and String.fromCharCode splicing to reconstruct the identifiers 'constructor', 'require', and 'module' at runtime. The code resolves Function via yLb[kqz] (a string-shuffled property lookup for 'constructor'), uses that Function constructor to build a decoder from one shuffled blob, decodes a second scrambled blob into JS source, and invokes that source via Function(...)(3004). It also assigns the CommonJS require and module bindings to globalThis (global[require]=require; global[module]=module), giving the decoded code access to any Node built-in (network, fs, child_process) regardless of how the package is imported. None of this behavior is documented in the README or exposed through the advertised API. The combination of multi-layer obfuscation, visual concealment via tab padding, dynamic eval of decoded literals, and forced global exposure of require/module is the canonical shape of a hidden remote-code-execution backdoor in an npm utility package — the decoded payload runs whenever calculateTokenPrice is called by a consumer.

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-2026-6440?

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-2026-6440 is a malicious package: tokenization-util (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-2026-6440/ (Markdown: https://insights.sbomify.com/MAL-2026-6440/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6440

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6440/
Summaries are generated and may contain mistakes; the official description above is the record.