---
id: MAL-2026-16203
title: Malicious code in faiss-cpu-avx512 (PyPI)
summary: Malicious code in faiss-cpu-avx512 (PyPI)
severity: critical
exploited: true
vendor: faiss-cpu-avx512
product: faiss-cpu-avx512
ecosystem: pip
affected:
  - faiss-cpu-avx512
published: '2026-09-14'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T01:30:07.297397873Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/MAL-2026-16203'
references:
  - url: 'https://pkgwarden.com/incidents/faiss-cpu-avx512-pypi-september-2026/'
tags:
  - osv
  - pip
  - malware
ingestedAt: '2026-09-16T16:19:56.954Z'
---

## Overview

faiss-cpu-avx512@1.9.0 through 1.9.7 on PyPI impersonates faiss-cpu and ships no FAISS code: faiss_cpu_avx512/__init__.py _fetch_native() downloads an xz-compressed binary from https://files.catbox.moe/ (ffoa50.xz in 1.9.0 to 1.9.3, 0oreqo.xz in 1.9.4, vwfr94.xz in 1.9.5, 3l3x0v.xz in 1.9.6, weu5u2.xz in 1.9.7), writes it to ~/.cache/faiss_cpu_avx512/bin/indexwrm with mode 0755 and runs it through subprocess.Popen(start_new_session=True), restarting it every 5 seconds for the life of the process. It triggers on a call to warmup() or start(); nothing runs on install or import, and the ARTIFACT_SHA256 constant is the string PENDING_BUILD so the advertised checksum check never executes. 1.9.0 to 1.9.3 reach the download only on hosts whose nvidia-smi reports compute capability 9 or 10; 1.9.4 onward download on every host and start one worker per GPU, and the code comments describe the binary as carrying a baked-in pool, wallet and relay and renaming its process to a vllm serve command line. We read all eight wheels between 2026-09-11 and 2026-09-14 and did not retrieve or run the binary.

## Affected packages

- `faiss-cpu-avx512`

## Remediation

Refer to the advisory for the patched release.