# MAL-2026-16309: Malicious code in npmscript_tesstalert_unpkg (npm)


- **Type:** Malicious package
- **Package:** `npmscript_tesstalert_unpkg` (npm)
- **Published:** 21 Sep 2026
- **Also known as:** GHSA-xvj9-j5xj-9f5p

## What is MAL-2026-16309?

MAL-2026-16309 is a malicious package in npmscript_tesstalert_unpkg, published on 21 Sep 2026. 

### Official description

The package ships a single script exposed via the `unpkg` field for CDN loading into web pages. When executed in a browser, the script reads `document.cookie` and assigns `window.location.href` to `https://webhook.site/4c14c8e4-721e-471d-807c-1a2aa216512a/` concatenated with the cookie value, causing the browser to navigate to that attacker-controlled endpoint carrying the victim's cookies. The identifiers `location`, `href`, and `cookie` are assembled from split fragments (`"loca"+"tion"`, `"hr"+"ef"`, `"coo"+"kie"`) to hide the sensitive property accesses from string-based scanners. Any page that loads this file via unpkg or bundles it exfiltrates its cookies to the hardcoded webhook.site collector.

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-2026-16309?

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-2026-16309 is a malicious package: npmscript_tesstalert_unpkg (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-2026-16309/ (Markdown: https://insights.sbomify.com/MAL-2026-16309/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-16309

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-16309/
Summaries are generated and may contain mistakes; the official description above is the record.