MAL-2026-12351

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-common-tokens/MAL-2026-12351.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12351
Published
2026-08-05T12:36:29Z
Modified
2026-08-05T13:35:03.806302074Z
Summary
Malicious code in checkout-common-tokens (npm)
Details

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

Source: amazon-inspector (fe0e9681cb5e7a197ca8d77ba29e20a4709fa0ff476f2ffb02f935785c6633e0)

On require, index.js loads ext.js which selects a platform-specific payload URL from a rotating list of Cloudflare Workers subdomains (hosts assembled at runtime by joining split string fragments such as ["oob-worker.cf101-adf.workers.d","ev"].join("")), fetches the binary over HTTPS, writes it to /tmp/.cache<hex> on Unix or %TEMP%\dotnetdiag<hex>.exe on Windows, chmods 0o755, and spawns it detached via /bin/sh -c or cmd.exe. If the HTTPS fetch fails, ext.js falls back to a DNS-TXT covert channel against *.dl.well1.site: a chunk-count TXT lookup at c.<domain> followed by N.<domain> TXT queries whose base64-decoded concatenation is written to disk and executed. Staging file names (.cache, dotnetdiag.exe,.analytics_state) are chosen to mimic legitimate diagnostic/telemetry artifacts, and destination hostnames are string-split obfuscated to defeat static inspection. The fetched payload is opaque, unpinned, unrelated to any documented package purpose, and executed with the installer's privileges immediately on import.

Database specific 
{
    "malicious-packages-origins": [
        {
            "modified_time": "2026-08-05T12:36:29Z",
            "id": "IN-MAL-2026-014726",
            "import_time": "2026-08-05T13:08:41.260205194Z",
            "versions": [
                "20.1.6"
            ],
            "source": "amazon-inspector",
            "sha256": "fe0e9681cb5e7a197ca8d77ba29e20a4709fa0ff476f2ffb02f935785c6633e0"
        }
    ]
}
References
Credits

Affected packages

npm / checkout-common-tokens

Package

Name
checkout-common-tokens
View open source insights on deps.dev
Purl
pkg:npm/checkout-common-tokens

Affected ranges

Affected versions

20.*
20.1.6

Database specific

cwes 
[
    {
        "cweId": "CWE-506",
        "name": "Embedded Malicious Code",
        "description": "The product contains code that appears to be malicious in nature."
    }
]
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-common-tokens/MAL-2026-12351.json"
indicators 
{
    "package_integrity": [
        {
            "hashes": {
                "sha512_sri": "sha512-Qb6mnzrOFluSFNiPurpdnLEQ6tCmGT27Vqqn2uDWzbXJiMn6kgYqu5pl2d4AaPajfsAYHy8BNVvPWnJ3537Q1w==",
                "sha1": "0e2d4bd0b155abe69ddaf66a2c97788fc5a098df"
            },
            "filename": "checkout-common-tokens-20.1.6.tgz"
        }
    ],
    "evidence_files": [
        {
            "path": "_ext.js",
            "tlsh": "15a186aa1166701d4bb0d7e4ca175416f65bf6637380c694fb9ca5884fb322483f2eec",
            "sha256": "260655ff4a7da8d705d16582c59b04c7712693b702df3c0743501e4df27ccb0d"
        }
    ]
}