# MAL-2026-16363: Malicious code in blue-string-formatter-utilss (npm)


- **Type:** Malicious package
- **Package:** `blue-string-formatter-utilss` (npm)
- **Published:** 21 Sep 2026

## What is MAL-2026-16363?

MAL-2026-16363 is a malicious package in blue-string-formatter-utilss, published on 21 Sep 2026. 

### Official description

The package advertises itself as string-formatting utilities but ships no formatter code. Its main entry `payload.js` is an IIFE that creates a `<script>` element with `src='https://xss.report/c/k3rne111'` and appends it to `document.body`, causing an attacker-controlled remote script to be fetched and executed whenever the module is loaded in a DOM context. xss.report is a known XSS payload-delivery service. The name-versus-behavior mismatch (a 'string formatter' whose only behavior is a remote script loader) is a typosquat cover story rather than legitimate functionality.

## What should I do about MAL-2026-16363?

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-2026-16363 is a malicious package: blue-string-formatter-utilss (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-2026-16363/ (Markdown: https://insights.sbomify.com/MAL-2026-16363/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-16363

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-16363/
Summaries are generated and may contain mistakes; the official description above is the record.