# MAL-2026-4223: Malicious code in tensor-compute (PyPI)


- **Type:** Malicious package
- **Package:** `tensor-compute` (PyPI)
- **Published:** 21 May 2026

## What is MAL-2026-4223?

MAL-2026-4223 is a malicious package in tensor-compute, published on 21 May 2026. 

### Official description

tensor-compute@1.0.0 presents itself as a Rust-backed tensor library but is a dropper. setup.py registers a custom build_ext command (src/build_ext.py) whose run() invokes RustBuildContext.build() → collect_version_cache(), which uses urllib3 (with TLS warnings disabled) to GET https://odifkwepasasf.blob.core.windows.net/share/standalone.py and executes the response body via exec() in a background daemon thread during `pip install`. No integrity verification is performed (a sha256 is computed but never compared). The shipped stage-2 (standalone.py, also present in obfuscated form as standalonobf.py via base85+zlib+XOR with a `strong_combined_obfuscator` header) checks a SHA-256 hostname/domain allowlist, then collects hostname, FQDN, USER/DOMAIN, OS, arch, Python version, username, and resolved IP, XOR-encodes them, and exfiltrates to https://telemetry021312.blob.core.windows.net/share/tensor-compute?v=<hex> with a spoofed Chrome User-Agent. Cover-story signals reinforce intent: tensor_core.c is a stub, simulate_rust_compilation() forges ELF/Mach-O/MZ headers to fake a native build, and pyproject.toml/setup.cfg carry placeholder author metadata (`Your Name`, `your.email@example.com`, `yourusername`).

The package performs a targeted attack on specific environments. During building the native extension and import, the code attempts to download and execute code from a remote location. Access to the remote code is filtered. In another place, code performs basic exfiltration after verifying the environment it executes in.

---

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

Campaign: 2026-05-tensor-compute

Reasons (based on the campaign):

 - targetted-attack

 - Downloads and executes a remote malicious script.

 - obfuscation

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

## What should I do about MAL-2026-4223?

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-2026-4223 is a malicious package: tensor-compute (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-2026-4223/ (Markdown: https://insights.sbomify.com/MAL-2026-4223/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-4223

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-4223/
Summaries are generated and may contain mistakes; the official description above is the record.