Malicious code in css-flow-render-shim (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.

[email protected] was published to npm on 2026-10-06 22:49 UTC by user brahimhamidi (the account's only package). It is described as a CSS polyfill but contains none: index.js is an empty module (byte-identical to the index.js of [email protected]) and payload.min.css is 15 bytes. payload.bundle.min.js carries the payload and runs at require time as a top-level IIFE; it first deletes its own require.cache entries so that it runs again on every require. Behavior: (1) obtains child_process through require('child_process'), require('node:child_process') or a freshly constructed Module instance if both are blocked (lines 29-31); (2) runs whoami, id, uname -a, env (first 100 lines, 2,000 characters sent), ifconfig || ip addr, and cat /etc/hosts with execSync and sends each output, together with os.hostname() and the tag vector=registryLibrariesTopology, to https://webhook.site/69bcd627-1871-4dda-b880-83b37ceac418 through both fetch and https.get (lines 12-56); the env step exfiltrates the host's environment variables, including any tokens; (3) sends a beacon tagged topology-rce with the Node version, platform, process id and package name (line 60); (4) exports Proxy objects under Wix-internal module names (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry, dataBindingRegistry, autoCompleteRegistry, thunderboltBuilderRegistry, thunderboltPreviewRegistry), and the two rb_*.thunderbolt.manifest.min.json files list the payload under https://unpkg.com/[email protected]/, which indicates a dependency-confusion attempt against that organization's private packages (lines 65-98). Trigger: on import (require). Type: information stealer (host identity, network configuration and environment variables). Same collector path as [email protected] (published 2026-10-06 20:21 UTC by user hissakdx92), which performs port scanning and host reconnaissance for the same target, and same payload family as [email protected] and css-eqxcdx-polyfill. --- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (f008c8756b09bb1840b05eafe5a30432475f6cc2d5a10064a42920059e8784fd) The package publishes an empty index.js stub but ships Thunderbolt manifests that register payload.bundle.min.js as the bundle for core Wix components across the thunderbolt/wixui and thunderbolt/dsgnsys namespaces (Container, MasterPage, Section, StylableButton, WRichText, and others), and the bundle exports factories under names like thunderboltRegistry, editorRegistry, and corvidRegistry. When a Wix Thunderbolt build pipeline resolves this name from the public registry instead of the intended internal package, payload.bundle.min.js is loaded and its top-level IIFE executes immediately. The IIFE uses child_process.execSync to run whoami, id, uname -a, env | head -100, ifconfig/ip addr, and cat /etc/hosts, then URL-encodes each output along with hostname, node version, platform, and pid and sends it via https.get to a hardcoded collector at https://webhook.site/69bcd627-1871-4dda-b880-83b37ceac418. The payload also iterates require.cache and deletes every entry whose path contains payload, rb_wixui, or rb_dsgnsys so the recon routine re-fires on each subsequent require within a long-running build process. The combination of a hollow public package impersonating an internal Wix shim, Thunderbolt-shaped manifests, host and environment reconnaissance via shell commands, exfiltration to an attacker-controlled webhook.site endpoint, and require.cache tampering is a dependency-confusion attack against Wix build systems.

Source published

8 Oct 2026 03:38:22 UTC

Source modified

8 Oct 2026 22:45:07 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.