---
id: MAL-2026-18093
title: Malicious code in workcalender (PyPI)
summary: Malicious code in workcalender (PyPI)
severity: critical
exploited: true
vendor: workcalender
product: workcalender
ecosystem: pip
affected:
  - workcalender
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T13:30:03.631651278Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/MAL-2026-18093'
references:
  - url: 'https://bad-packages.kam193.eu/pypi/package/workcalender'
tags:
  - osv
  - pip
  - malware
ingestedAt: '2026-10-21T11:54:42.739Z'
---

## Overview


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_-= Per source details. Do not edit below this line.=-_

## Source: kam193 (9a336c0fa7a5b3ee5f036d678c8c0f0d549135a08d05549ee92cb11b1a7f78fa)
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.


## Affected packages

- `workcalender`

## Remediation

Refer to the advisory for the patched release.