MAL-2026-17476 Malicious code in css-anchor-pos-fallback (npm)
Malicious package
Published
MAL-2026-17476 is a malicious package: css-anchor-pos-fallback (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-2026-17476/ (Markdown: https://insights.sbomify.com/MAL-2026-17476/index.md)
- Package
- css-anchor-pos-fallback
- Registry
- npm
What is MAL-2026-17476?
MAL-2026-17476 is a malicious package in css-anchor-pos-fallback, published on 4 Oct 2026.
Official description
The package advertises itself as a CSS anchor-position polyfill but on require executes an IIFE in thunderboltRegistry.js that runs
id, whoami, uname -a, ifconfig/ip addr, and reads /etc/hosts, then POSTs the collected output along with hostname, platform, and Node version via fetch to the hardcoded external endpoint http://dxpoc.gt.tc/callback.php/. The module also exports keys named after Wix thunderbolt internal registries (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, etc.) with a bundled manifest referencing a parastorage.com unpkg URL, a shape consistent with dependency-confusion targeting of an internal Wix build pipeline. The advertised polyfill purpose is unrelated to shell execution, host reconnaissance, or outbound beaconing.What should I do about MAL-2026-17476?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.