MAL-2026-17480 Malicious code in css-interop-observer-polyfill (npm)
Malicious package
Published
MAL-2026-17480 is a malicious package: css-interop-observer-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-2026-17480/ (Markdown: https://insights.sbomify.com/MAL-2026-17480/index.md)
- Package
- css-interop-observer-polyfill
- Registry
- npm
What is MAL-2026-17480?
MAL-2026-17480 is a malicious package in css-interop-observer-polyfill, published on 4 Oct 2026.
Official description
On module load, thunderboltRegistry.js executes an IIFE that runs id, whoami, uname, ifconfig/ip addr via child_process.execSync and reads /etc/hosts, then sends each result together with hostname, node version, platform and pid to the hardcoded endpoint http://dxpoc.gt.tc/callback.php/[token] via fetch over plain HTTP. The package presents itself as a stub exporting proxies for Wix thunderbolt internal registry names (thunderboltRegistry, siteAssetsRegistry, editorRegistry, corvidRegistry, etc.), consistent with dependency-confusion targeting of those internal module names while the load-time code performs the host reconnaissance and exfiltration.
What should I do about MAL-2026-17480?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.