# MAL-2026-5279: Malicious code in uprobe (PyPI)


- **Type:** Malicious package
- **Package:** `uprobe` (PyPI)
- **Published:** 6 Jun 2026
- **Also known as:** PYSEC-2026-611

## What is MAL-2026-5279?

MAL-2026-5279 is a malicious package in uprobe, published on 6 Jun 2026. 

### Official description

The package installs `uprobe-setup.pth`, which Python auto-loads at every interpreter startup in any environment where the wheel is present. The.pth contents alias stdlib modules to single-underscore short names (`_O`, `_T`, `_o`, `_s`, `_u`, `_p`, `_y`, `_g`, `_zf`) and wrap the payload in `exec('...')` gated by a `/tmp/.bun_ran` sentinel. The payload globs for a sibling `_index.js` under the package directory, downloads the Bun JavaScript runtime ZIP from `https://github.com/oven-sh/bun/releases/download/bun-v1.3.13/bun-{platform}-{arch}.zip` to `/tmp/b/bun`, chmods it 0o775, and invokes `subprocess.run([bun, 'run', _index.js])`. This is an alternate-runtime dropper: a foreign runtime is fetched and used to execute bundled JavaScript that is opaque to any Python-side review. The behavior fires unconditionally on `python` startup (not just on explicit tool invocation), runs outside pip's build isolation, and the obfuscation + exec-on-string + sentinel-gated one-shot pattern is canonical evasion shape. The advertised purpose of the package (a FISH-probe design tool) has no need for a JavaScript runtime.

Versions 0.1.3, 0.1.4 were compromised.

Compromised packages start an obfuscated infostealer. The infostealer is a heavily obfuscated JavaScript code executed using Bun runtime on Python startup. It collectes all kinds of sensitive data, including API keys, credentials to package repositories, cryptocurrency assets, password manager data. Infostealer actively queries online services to collect additional secrets as well as attempts to gain persistence and spread further by publishing infected packages using collected credentials. Data are exfiltrated likely using Github. The code seems to threaten to wipe the user's data if it detects invalid GitHub tokens. Cleanup should be done with caution.

It seems to be related to the recent Mini Shai Hulud campaign.

---

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

Campaign: 2026-06-compr-woodpecker

Reasons (based on the campaign):

 - compromised-package

 - exfiltration-env-variables

 - exfiltration-cloud-tokens

 - exfiltration-credentials

 - abuses-pth

 - obfuscation

 - infostealer

 - The package contains code to detect if it is running in a sandbox environment.

 - exfiltration-crypto

 - files-exfiltration

 - destructive-actions

## What should I do about MAL-2026-5279?

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-2026-5279 is a malicious package: uprobe (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-2026-5279/ (Markdown: https://insights.sbomify.com/MAL-2026-5279/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-5279

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-5279/
Summaries are generated and may contain mistakes; the official description above is the record.