---
id: MAL-2026-18092
title: Malicious code in test-workalendar-internal (PyPI)
summary: Malicious code in test-workalendar-internal (PyPI)
severity: critical
exploited: true
vendor: test-workalendar-internal
product: test-workalendar-internal
ecosystem: pip
affected:
  - test-workalendar-internal
published: '2026-10-20'
updated: '2026-10-20'
sourceUpdated: '2026-10-20T18:30:11.131291138Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/MAL-2026-18092'
references:
  - url: 'https://bad-packages.kam193.eu/pypi/package/test-workalendar-internal'
  - url: 'https://pypi.org/project/test-workalendar-internal/0.0.3/'
tags:
  - osv
  - pip
  - malware
ingestedAt: '2026-10-21T11:54:42.738Z'
---

## Overview


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

## Source: amazon-inspector (06eccee3c04982c18f9f348949477e1540d3e63eab7ae66f5d851428d0308597)
test-workalendar-internal 0.0.3 ships a custom Hatchling build hook that runs during `pip install` (sdist/wheel build). The hook downloads two standalone binaries — ttyd from github.com/tsl0922/ttyd and cloudflared from github.com/cloudflare/cloudflared — to /tmp/ttyd and /tmp/cloudflared, chmods them executable, and spawns ttyd bound to 127.0.0.1:7681 serving an interactive `bash` shell protected only by a generated basic-auth user/password. It then launches `cloudflared tunnel --url http://127.0.0.1:7681`, parses the resulting `*.trycloudflare.com` URL from cloudflared's stdout, and POSTs a JSON payload containing the tunnel URL, username, and password to the hardcoded collector https://webhook.site/f03cbdbe-704b-4932-a0a7-847d749c19b6. The combined effect is a fully automatic install-time remote shell on the installer's host: a remote party receives the public tunnel URL and basic-auth credentials and can interact with bash on the installer's machine. The package's declared purpose (a weekday/calendar helper) is unrelated to web terminals or tunnels.

## Source: kam193 (9f36e976d0fcf254def6da62e0090bfb2dbdf76176ed316655574408c25cb9a0)
During build, the package creates a web-sharable terminal session and exposes it via a Cloudflare tunnel to the attacker.


---

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

- `test-workalendar-internal`

## Remediation

Refer to the advisory for the patched release.