MAL-2026-12642

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/claims-shared/MAL-2026-12642.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12642
Published
2026-08-05T14:01:54Z
Modified
2026-08-05T14:36:04.270593001Z
Summary
Malicious code in claims-shared (npm)
Details

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

Source: amazon-inspector (234e56b5a35fe88da0e1c1618cfa81e163b8a959d3c5b2e50b8de8bee67b6404)

On require of claims-shared, index.js loads polyfill.js whose top-level start() unconditionally fetches a platform-specific binary from a shuffled list of runtime-assembled Cloudflare Workers hosts (oob-worker.cf100-.workers.dev, oob-worker.cf101-.workers.dev, oob-worker.cf102-.workers.dev, oob-worker.cf103-.workers.dev), with a DNS TXT chunked-download fallback via sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru subdomains. Destination hostnames are reconstructed from split string arrays (e.g. ["oob-worker.cf100-416.workers.","de","v"].join("")) to evade static matching. The fetched bytes are written to /var/tmp/.cache<hex> on Unix or %TEMP%\dotnetdiag<hex>.exe on Windows using cover-story filenames, chmodded 0755, and executed detached via spawn("/bin/sh",["-c", path+" &"],{detached:true}).unref() or spawn("cmd",...). Payload is executed only if larger than 1000 bytes. Behavior fires on plain require() of the package with no user action.

Database specific 
{
    "malicious-packages-origins": [
        {
            "sha256": "234e56b5a35fe88da0e1c1618cfa81e163b8a959d3c5b2e50b8de8bee67b6404",
            "id": "IN-MAL-2026-015136",
            "modified_time": "2026-08-05T14:01:54Z",
            "source": "amazon-inspector",
            "import_time": "2026-08-05T14:20:05.685984753Z",
            "versions": [
                "35.7.1"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / claims-shared

Package

Name
claims-shared
View open source insights on deps.dev
Purl
pkg:npm/claims-shared

Affected ranges

Affected versions

35.*
35.7.1

Database specific

indicators 
{
    "evidence_files": [
        {
            "sha256": "ba2cc522d3ac3982045f70ad1de511be44bba1b6f15cef578f293350e8e46e7e",
            "path": "_polyfill.js",
            "tlsh": "e1a1979a15a6701c8bb0ebe4c7078816f65af6533680c2d4f79ca9945f7352483b2efc"
        }
    ],
    "package_integrity": [
        {
            "hashes": {
                "sha512_sri": "sha512-507PM4oHcBCHzWzDQ/Czf4IrmVz8Om88RWbbHy9b2lWbmSng+poIpzbvkx+vt7oTJ+jqr/NhEk1GJ8jWoQTrjQ==",
                "sha1": "e6db5257471f1e5262d7b4634631039e3a74ab62"
            },
            "filename": "claims-shared-35.7.1.tgz"
        }
    ]
}
cwes 
[
    {
        "name": "Embedded Malicious Code",
        "description": "The product contains code that appears to be malicious in nature.",
        "cweId": "CWE-506"
    }
]
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/claims-shared/MAL-2026-12642.json"