MAL-2026-17554

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-mpmdds-polyfill/MAL-2026-17554.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-17554
Published
2026-10-05T03:36:46Z
Modified
2026-10-05T04:15:05Z
Summary
Malicious code in css-mpmdds-polyfill (npm)
Details

-= Per source details. Do not edit below this line.=-

Source: amazon-inspector (4bac0cb0a2c693985668a890ff2ace72ff2d00dac60bc5470a77160c4d765106)

The package presents itself as a CSS polyfill but ships thunderboltRegistry.js which runs an IIFE at module load. The IIFE acquires child_process via multiple fallbacks (require('child_process'), require('node:child_process'), and a synthesized Module constructor), executes shell commands to collect host identity (id, whoami, uname -a, ifconfig/ip addr, /etc/hosts) along with os.hostname, Node version, platform and pid, and transmits each result via fetch() as query parameters to the hardcoded endpoint http://dxpoc.gt.tc/callback.php/bb8968d0f67000433bf7005dd5ad2d1f over plaintext HTTP to a free-DNS (gt.tc) host unrelated to any CSS polyfill functionality. The IIFE also enumerates require.cache and deletes entries containing 'thunderboltRegistry' so the payload re-executes on every require rather than being memoized. registry-manifest.min.json maps multiple Wix/thunderbolt internal registry module names (siteAssetsRegistry.js, editorRegistry.js, and others) all to the same thunderboltRegistry.js payload mirrored on static.parastorage.com's unpkg mirror, consistent with a dependency-confusion / typosquat targeting the Wix thunderbolt ecosystem. The package stubs a Wix-ecosystem API surface via Proxy to appear functional while the exfil IIFE runs. The package name resembles a CSS polyfill but the shipped behavior is host reconnaissance and exfiltration with cache-busting evasion.

Database specific 
{
    "malicious-packages-origins":  [
        {
            "id":  "IN-MAL-2026-021021",
            "import_time":  "2026-10-05T03:57:39.34766112Z",
            "modified_time":  "2026-10-05T03:36:46Z",
            "sha256":  "4bac0cb0a2c693985668a890ff2ace72ff2d00dac60bc5470a77160c4d765106",
            "source":  "amazon-inspector",
            "versions":  [
                "1.0.0"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / css-mpmdds-polyfill

Package

Name
css-mpmdds-polyfill
View open source insights on deps.dev
Purl
pkg:npm/css-mpmdds-polyfill

Affected ranges

Affected versions

1.*
1.0.0

Database specific

cwes 
[
    {
        "cweId":  "CWE-506",
        "description":  "The product contains code that appears to be malicious in nature.",
        "name":  "Embedded Malicious Code"
    }
]
indicators 
{
    "evidence_files":  [
        {
            "path":  "thunderboltRegistry.js",
            "sha256":  "a485cb48081ea590cab385a405886cfe6f30af7d415f30bc8d7937ace461b928",
            "tlsh":  "e87154a5b99df02065c33438cb7f4049b4bbc6672d6caee0744899b01f7985c01be6f8"
        },
        {
            "path":  "registry-manifest.min.json",
            "sha256":  "1447737dc08969f2fbeb8da54a73ce3a3f7287c8b93a8c01d0b8cca6eeb3e2be",
            "tlsh":  "ae0170dd0d0a51ff1bc0998f5406fb0ae6034dc60ceee272592155a078681e112fa7ef"
        }
    ],
    "package_integrity":  [
        {
            "filename":  "css-mpmdds-polyfill-1.0.0.tgz",
            "hashes":  {
                "sha1":  "413d05dfc5b96e4731170bc5781dde591bb276bf",
                "sha512_sri":  "sha512-w3/uJzPKqV/5YRAe2HQ6YmJwJTqlSWvsONxbsebe0bA1oC8o9P34FxYDCoUEm0z8HWCtCGDves6qUxlPttrSSA=="
            }
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-mpmdds-polyfill/MAL-2026-17554.json"