Malicious code in css-reading-display-polyfill (npm)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

css-reading-display-polyfill is described as a CSS polyfill but contains no polyfill code. When its thunderboltRegistry.js is loaded, it runs `id`, `whoami`, `uname -a`, `env`, `ifconfig` and `cat /etc/hosts` and sends the output with the hostname to a webhook.site collector. The file also exports stubs named after Wix Thunderbolt registry modules. The environment variables are sent as well, so tokens and API keys stored in them can be leaked. --- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (a06a8966ab81cea21f3e94074bcdb0d72ea55a96be2d03989e12aa2f4d86ad66) thunderboltRegistry.js runs an IIFE at module load that invokes child_process.execSync to collect host identity (id, whoami, uname), the first 2000 bytes of the environment (env | head -100), network interfaces (ifconfig), and /etc/hosts, then transmits the results together with the hostname and Node version to a hardcoded webhook.site URL (https://webhook.site/69bcd627-1871-4dda-b880-83b37ceac418) via https.get and fetch. The package exports proxies for internal Wix thunderbolt registry names (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, dataBindingRegistry, and others) with a manifest pointing at static.parastorage.com/unpkg/, and the beacon is labelled beacon=rce-poc, consistent with a dependency-confusion probe against Wix build infrastructure. The exfiltrated environment typically contains CI secrets and cloud credentials, giving an installer-side credential-theft blast radius wherever the build pipeline resolves these internal names to this package.

Source published

8 Oct 2026 03:38:12 UTC

Source modified

8 Oct 2026 05:00:05 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

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