# MAL-2026-5519: Malicious code in requests-toolbelt-plus (PyPI)


- **Type:** Malicious package
- **Package:** `requests-toolbelt-plus` (PyPI)
- **Published:** 10 Jun 2026

## What is MAL-2026-5519?

MAL-2026-5519 is a malicious package in requests-toolbelt-plus, published on 10 Jun 2026. 

### Official description

The package impersonates the popular `requests-toolbelt` library but ships an empty `requests_toolbelt_plus/__init__.py` and places its real logic in `setup.py`. On `pip install`, setup.py checks `/proc/version` for WSL markers and, when matched, opens a TCP socket to the hardcoded IP 185.184.192.205 on port 4444, sends a JSON beacon containing `os.getlogin()`, `os.uname().nodename`, and `os.getcwd()`, then spawns a background thread that reads JSON commands from the socket and executes them via `subprocess.run(cmd, shell=True, capture_output=True, text=True)`, returning stdout/stderr to the operator — full remote command execution against the installer's machine. setup.py also appends a Python one-liner to `~/.bashrc` that re-opens the same socket, `dup2`s stdio onto it, and execs `/bin/bash -i`, giving the attacker a persistent interactive reverse shell that fires on every new login shell and survives package uninstall. The WSL-only gating is a deliberate evasion to stay dormant on non-WSL maintainer machines and execute only on targeted Windows-Subsystem-for-Linux developer hosts.

Installing the package or importing the module exfiltrates basic information about the host, and the package has no other purpose.

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Category: PROBABLY_PENTEST - Packages looking like typical pentest packages, but also anything that looks like testing, exploring pre-prepared kits, research & co, with clearly low-harm possibilities.

Campaign: GENERIC-standard-pypi-install-pentest

Reasons (based on the campaign):

 - The package contains code to exfiltrate basic data from the system, like IP or username. It has a limited risk.

 - The package overrides the install command in setup.py to execute malicious code during installation.

## What should I do about MAL-2026-5519?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-5519 is a malicious package: requests-toolbelt-plus (PyPI). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-5519/ (Markdown: https://insights.sbomify.com/MAL-2026-5519/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5519

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-5519/
Summaries are generated and may contain mistakes; the official description above is the record.