# MAL-2026-18102: Malicious code in semveer (PyPI)


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

## What is MAL-2026-18102?

MAL-2026-18102 is a malicious package in semveer, published on 20 Oct 2026. 

### Official description

The sdist for 'semveer' ships an inert module (semveer/__init__.py contains only a __version__ stub) and places all runtime behavior inside setup.py's install hook. On pip install, setup.py calls urllib.request.urlretrieve against https://c2-worker.crawlnet-claim.workers.dev/dl/pyupd, writes the opaque payload to a temporary file, and launches it via subprocess.Popen with start_new_session=True as a detached process. The fetch is wrapped in a bare try/except that suppresses errors, there is no hash or signature verification, the version is not pinned, and the destination host is unrelated to any declared publisher or project homepage. The package name is a one-character edit of the widely used 'semver' name, consistent with a typosquat lure whose only purpose is to trigger the install-time dropper.

During installation, package downloads and executes malware.

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

Campaign: 2026-10-semvver

Reasons (based on the campaign):

 - Downloads and executes a remote executable.

 - malware

 - typosquatting

## What should I do about MAL-2026-18102?

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-2026-18102 is a malicious package: semveer (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-2026-18102/ (Markdown: https://insights.sbomify.com/MAL-2026-18102/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-18102

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-18102/
Summaries are generated and may contain mistakes; the official description above is the record.