---
id: "MAL-2026-18298"
kind: "package"
aliases: ["MAL-2026-18298"]
title: "Malicious code in claudeopusfile (PyPI)"
severity: "critical"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "claudeopusfile", "fixed": [], "affected": "= 0.1.1; = 0.1.2", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["malicious", "package"]
not_affected_if: []
published_at: "2026-10-25T23:35:59+00:00"
first_seen_at: "2026-10-26T20:52:03+00:00"
updated_at: "2026-10-26T21:05:48+00:00"
sources: [{"source": "osv-malicious", "url": "https://osv.dev/vulnerability/MAL-2026-18298", "first_seen_at": "2026-10-26T20:52:03+00:00"}]
---

# Malicious code in claudeopusfile (PyPI)

## Affected

- pypi:claudeopusfile affected = 0.1.1; = 0.1.2 fixed ?

## Timeline

- 2026-10-26T20:52:03+00:00 osv-malicious https://osv.dev/vulnerability/MAL-2026-18298

## From the sources

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

## Source: amazon-inspector (de2f0d45d8a2c0489d082d86a91c63fc5cad53f891b3dd1e976cd7479344c65f)
setup.py imports claudeopusfile.compat._ensure_compat during pip install. compat.py constructs the string 'exec' from a chr-code tuple (chr(101),chr(120),chr(101),chr(99)) and invokes it via getattr(builtins, _RUN)(compile(code, '<claudeopusfile-compat>', 'exec'),...) on content produced by zlib.decompress(base64.b85decode(_shimdata.DATA)) — an opaque base85+zlib blob shipped in claudeopusfile/_shimdata.py. An in-source comment states the getattr indirection is intended to hide the exec call from scanners, and environment variables (CLAUDEOPUSFILE_TELEMETRY=0, DAS_STAGED=1) act as kill switches that suppress execution in instrumented environments. The package additionally ships claudeopusfile/_payload.py containing a second large opaque PAYLOAD string together with security.py implementing PBKDF2+ChaCha20+HMAC sign/unsign helpers (context tag b'coe.'), providing a signed-channel decryption path for a staged second payload. Decoded content runs with the installer's privileges on `pip install`. The package's advertised purpose (prompt-generator utility) has no need to decode and execute an opaque blob at install time.

## Source: kam193 (9a776d104d66cbeec1283bd7a7e9decc15da19a1946dd27c7d7ca632a6cdc2f2)
During installation, obfuscated code is used to fetch code hidden in an image containing a Python application with a native extension module. This module holds an obfuscated infostealer which collects sensitive data and exfiltrates them to a C2 server retrieved from transaction history in the Polygon blockchain.


---

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


Campaign: 2026-09-donutautosellsrc


Reasons (based on the campaign):


 - infostealer


 - Downloads and executes a remote executable.


 - obfuscation


 - The package contains code to detect if it is running in a sandbox environment.


 - malware


 - native-extension


 - steganography


 - c2-in-blockchain

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_