# MAL-2026-18093: Malicious code in workcalender (PyPI)


- **Type:** Malicious package
- **Package:** `workcalender` (PyPI)
- **Published:** 20 Oct 2026

## What is MAL-2026-18093?

MAL-2026-18093 is a malicious package in workcalender, published on 20 Oct 2026. 

### Official description

Analysis of the package's shipped files produced no indicators of installer-side harm: no install-time or import-time network I/O, no credential or environment scraping, no fetch-and-execute pattern, no lifecycle shell execution, no silent relay of caller data to a hardcoded destination, and no persistence or backdoor mechanism. The package appears to be a small or developmental release with no observable supply-chain attack surface.

This package contains a stub build-time helper, which in another package of the same uploader was already turned into a backdoor installation. While this package does not yet contain malicious code, it is clear it was uploaded with such intention and likely exploits dependency confusion.

---

Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.

Campaign: 2026-10-test-workalendar-internal

Reasons (based on the campaign):

 - backdoor

 - The package overrides the install command in setup.py to execute malicious code during installation.

## What should I do about MAL-2026-18093?

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-2026-18093 is a malicious package: workcalender (PyPI). 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-2026-18093/ (Markdown: https://insights.sbomify.com/MAL-2026-18093/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-18093

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-18093/
Summaries are generated and may contain mistakes; the official description above is the record.