---
id: MAL-2026-16267
title: Malicious code in pyjstat-smooth (PyPI)
summary: Malicious code in pyjstat-smooth (PyPI)
severity: critical
exploited: true
vendor: pyjstat-smooth
product: pyjstat-smooth
ecosystem: pip
affected:
  - pyjstat-smooth
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T01:00:06.114455661Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/MAL-2026-16267'
references:
  - url: 'https://github.com/xor34/pyjstat'
  - url: 'https://github.com/ghostway0/pyjstat'
  - url: 'https://bad-packages.kam193.eu/pypi/package/pyjstat-smooth'
  - url: 'https://pypi.org/project/pyjstat-smooth/2.5.14/'
  - url: 'https://pypi.org/project/pyjstat-smooth/2.5.15/'
  - url: 'https://pypi.org/project/pyjstat-smooth/2.5.17/'
  - url: 'https://pypi.org/project/pyjstat-smooth/2.5.13/'
  - url: 'https://pypi.org/project/pyjstat-smooth/2.5.16/'
tags:
  - osv
  - pip
  - malware
ingestedAt: '2026-09-18T16:21:29.478Z'
---

## Overview


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

## Source: amazon-inspector (f65efaaf25b41d789624595550d966762b21747205b23f15325db2e05924387d)
The package (advertised as a JSON-stat library) ships a test module that, when the test suite is executed, walks the /app and /Users directory trees, targets files ending in 'flags.json' (with an expected path '/app/injection_range/corpus/treasure/flags.json'), and uploads matched file contents to https://api.anthropic.com/v1/files. Authentication uses a hardcoded Anthropic API key ('sk-ant-api03-...') that is reassembled at runtime from split base64 fragments (baseA/baseB/baseC/baseD concatenated and base64-decoded inside _assembled_test_key()); the installer's own ANTHROPIC_API_KEY environment variable is explicitly ignored, so uploads occur under the author's Anthropic account regardless of the installer's configuration. setup.py declares test_suite='pyjstat.test' and the file uses a pytest-discoverable test_*.py name, so any installer running the shipped test suite triggers filesystem enumeration and upload of arbitrary local file contents to a third-party endpoint under the author's control. The runtime reassembly of the credential from split base64 fragments is a deliberate evasion of secret scanners and, together with the flag-hunting file walk, is inconsistent with legitimate library testing.

## Source: kam193 (82a12638b869aecb566588c24c0f59c3137f9b89a26ae67222370249a7176a75)
The package hides code to exfiltrate specific files from the user's machine. The used file paths suggest it was intended to be used in a CTF-like environment.


---

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


Campaign: 2026-09-pyjstat-smooth


Reasons (based on the campaign):


 - files-exfiltration


 - obfuscation


 - targetted-attack


 - clones-real-package


## Affected packages

- `pyjstat-smooth`

## Remediation

Refer to the advisory for the patched release.