Malicious code in css-flow-render-shim (npm)

{
  "id": "aa1c2ca0b8cffe029bd5c57173ee22a57899ed256f874c6cb60595ff3a60170c",
  "url": "https://osv.dev/vulnerability/MAL-2026-17655",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Malicious code in css-flow-render-shim (npm)",
    "summary": "css-flow-render-shim@1.0.0 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 css-jptvix-polyfill@1.0.0) 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",
    "evidence": "osv:MAL-2026-17655",
    "products": [
      {
        "name": {
          "value": "css-flow-render-shim",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "MAL-2026-17655",
      "aliases": [
        "MAL-2026-17655"
      ],
      "affected": [
        {
          "package": {
            "name": "css-flow-render-shim",
            "purl": "pkg:npm/css-flow-render-shim",
            "ecosystem": "npm"
          },
          "versions": [
            "1.0.0"
          ],
          "database_specific": {
            "cwes": [
              {
                "name": "Embedded Malicious Code",
                "cweId": "CWE-506",
                "description": "The product contains code that appears to be malicious in nature."
              }
            ],
            "source": "https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-flow-render-shim/MAL-2026-17655.json",
            "indicators": {
              "evidence_files": [
                {
                  "path": "payload.bundle.min.js",
                  "tlsh": "f78111a5a998b021a5c37478cb7f904ef4bb96632c6c6ed4b44c8ab12f3185c42b95f0",
                  "sha256": "2579c09d078991532f03cec0d53c7182ea1426a0faf465d7a9a93827b247578e"
                },
                {
                  "path": "rb_wixui.thunderbolt.manifest.min.json",
                  "tlsh": "f401a72681185d1a4e81393e31b3bf015d77a0a23d944f00c679d3de8fb96a170d2dc1",
                  "sha256": "58554c599280f131f74397c7630b5ab297891c73544d8f33748cde5e2c78dfc6"
                }
              ],
              "package_integrity": [
                {
                  "hashes": {
                    "sha1": "447d4119f3ceefc6904f917fc3c0273ffa903ec5",
                    "sha512_sri": "sha512-P7PIzY9n/e0SxCSAjQZQ/weGm92XudY5G146tKrPpjATDSV8nkEyFobT2AcZUNAGxXiAS5VW3yQoBpDwMPeHcg=="
                  },
                  "filename": "css-flow-render-shim-1.0.0.tgz"
                }
              ]
            }
          }
        }
      ],
      "modified": "2026-10-08T22:45:07.360812724Z",
      "provider": "osv",
      "references": [
        "https://www.npmjs.com/package/css-flow-render-shim/v/1.0.0"
      ],
      "provider_metadata": {
        "iocs": {
          "urls": [
            "https://webhook.site/69bcd627-1871-4dda-b880-83b37ceac418"
          ],
          "files": [
            {
              "note": "payload: runs on require, executes whoami/id/uname/env/ifconfig/cat /etc/hosts and sends the output to webhook.site",
              "paths": [
                "payload.bundle.min.js"
              ],
              "source": "PACKAGE_ARCHIVE",
              "digests": {
                "sha256": "2579c09d078991532f03cec0d53c7182ea1426a0faf465d7a9a93827b247578e"
              }
            },
            {
              "note": "manifest in Wix thunderbolt format pointing at this package on unpkg (dependency confusion)",
              "paths": [
                "rb_wixui.thunderbolt.manifest.min.json"
              ],
              "source": "PACKAGE_ARCHIVE",
              "digests": {
                "sha256": "58554c599280f131f74397c7630b5ab297891c73544d8f33748cde5e2c78dfc6"
              }
            }
          ],
          "domains": [
            "webhook.site"
          ]
        },
        "malicious-packages-origins": [
          {
            "id": "IN-MAL-2026-021116",
            "sha256": "f008c8756b09bb1840b05eafe5a30432475f6cc2d5a10064a42920059e8784fd",
            "source": "amazon-inspector",
            "versions": [
              "1.0.0"
            ],
            "import_time": "2026-10-08T03:50:28.94437226Z",
            "modified_time": "2026-10-08T03:38:22Z"
          }
        ]
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 107823,
  "published_at": "2026-10-08T03:38:22+00:00"
}