semveer

GHSA-xh78-qp67-j6mg

Malicious code in semveer (PyPI)

Details

**Severity:** Critical

**Affected versions:** `= 1.0.0`

## Source: amazon-inspector (d86237b957fd063a0e1fcf250a510b2fb9566ab48652e56fe787d2e1a02e351a)
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.

---

Credit: [OpenSSF](https://github.com/ossf/malicious-packages) ([source](https://github.com/ossf/malicious-packages/blob/e29c7e37b0612ba04bf703b601e4f2a2ac4a98de/osv/malicious/pypi/semveer/MAL-2026-18102.json))

**References:**
- https://github.com/ossf/malicious-packages/blob/e29c7e37b0612ba04bf703b601e4f2a2ac4a98de/osv/malicious/pypi/semveer/MAL-2026-18102.json
- https://pypi.org/project/semveer/1.0.0
- https://bad-packages.kam193.eu/pypi/package/semveer
- https://github.com/ossf/malicious-packages/blob/5b75048f63715357959b2e2456ba15740497bba3/osv/malicious/pypi/semveer/MAL-2026-18102.json
- https://www.virustotal.com/gui/file/e6d96b5500b232bea67f6f9046cfbc22d29a515c42d2af9523a15ebe8a7c4ab7
- https://github.com/ossf/malicious-packages/blob/65a30c2bd1748889a5fb95a96da4a49b781c4b60/osv/malicious/pypi/semveer/MAL-2026-18102.json
- https://github.com/advisories/GHSA-xh78-qp67-j6mg

Compromised versions (1)

= 1.0.0

Any computer that installed or ran a compromised version should be considered fully compromised. Rotate every secret on that machine from a clean environment.