# MAL-2026-6557: Malicious code in pkg-fallback (PyPI)


- **Type:** Malicious package
- **Package:** `pkg-fallback` (PyPI)
- **Published:** 28 Jun 2026

## What is MAL-2026-6557?

MAL-2026-6557 is a malicious package in pkg-fallback, published on 28 Jun 2026. 

### Official description

setup.py performs an unconditional urllib.request.urlopen() at install time to a hardcoded plaintext bare-IP endpoint http://157.254.194.200:8080/dependency-payload-1.0.0.tar.gz, with exceptions silently swallowed. This fires automatically during pip install (build/setup phase), confirming code execution on the installer's machine and disclosing the installer's network identity to attacker-controlled infrastructure. The distribution is published as 'pkg-fallback' but ships an unrelated 'string_kit' module described as 'string-kit' in README/PKG-INFO; the name/module divergence together with the install-time bare-IP beacon and the attacker-suggestive payload filename ('dependency-payload') is consistent with a dependency-confusion staging/enumeration package rather than a genuine utility.

Package exploits dependency confusion. A beacon request is used to report usage back, but no additional information are exfiltrated.

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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-beacon-dependency-confusion

Reasons (based on the campaign):

 - typosquatting

 - dependency-confusion

## What should I do about MAL-2026-6557?

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-2026-6557 is a malicious package: pkg-fallback (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-2026-6557/ (Markdown: https://insights.sbomify.com/MAL-2026-6557/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-6557

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-6557/
Summaries are generated and may contain mistakes; the official description above is the record.