Malicious code in postcss-gap-fallback-util (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.

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (5b54d5bd893bc377a77503059998e01ae3e338fd4d8ddac6fe2d7c71a3157cb5) The package is published as a PostCSS gap fallback utility but ships thunderboltRegistry.js, which executes an IIFE on module load. The IIFE runs whoami, id, and hostname via child_process.execSync, curls the AWS instance metadata service at http://169.254.169.254/latest/meta-data/ for IAM role, instance-id, availability zone, and local IPv4, and sends the results to https://webhook.site/0492a36c-4d7b-408a-865c-226db25987ba along with DNS beacons to a host under oast.live. A registry-manifest.min.json maps multiple Wix-internal registry names (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, dataBindingRegistry, thunderboltBuilderRegistry, thunderboltPreviewRegistry) to the same exfiltration file, and the module exports a Proxy returning no-op registry methods as a façade. The naming, manifest, and façade indicate a dependency-confusion payload targeting Wix build infrastructure; on any installer that requires one of the impersonated module names, shell identity, hostname, and (on EC2) AWS IAM role credentials/metadata are leaked to an attacker-controlled webhook and DNS collector.

Source published

4 Oct 2026 23:26:45 UTC

Source modified

4 Oct 2026 23:45:20 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

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.