---
id: "MAL-2026-18092"
kind: "package"
aliases: ["MAL-2026-18092"]
title: "Malicious code in test-workalendar-internal (PyPI)"
severity: "critical"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "test-workalendar-internal", "fixed": [], "affected": "= 0.0.1; = 0.0.2; = 0.0.3", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["malicious", "package"]
not_affected_if: []
published_at: "2026-10-20T13:00:38+00:00"
first_seen_at: "2026-10-26T20:52:00+00:00"
updated_at: "2026-10-26T21:05:48+00:00"
sources: [{"source": "osv-malicious", "url": "https://osv.dev/vulnerability/MAL-2026-18092", "first_seen_at": "2026-10-26T20:52:00+00:00"}]
---

# Malicious code in test-workalendar-internal (PyPI)

## Affected

- pypi:test-workalendar-internal affected = 0.0.1; = 0.0.2; = 0.0.3 fixed ?

## Timeline

- 2026-10-26T20:52:00+00:00 osv-malicious https://osv.dev/vulnerability/MAL-2026-18092

## From the sources

---
_-= 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.

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