MAL-2026-13946

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/date-fmt-helper-xz/MAL-2026-13946.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-13946
Published
2026-08-13T17:16:06Z
Modified
2026-08-13T17:30:12.568946138Z
Summary
Malicious code in date-fmt-helper-xz (npm)
Details

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

Source: amazon-inspector (b384650ec0fabdd01a7dfc513cccd25156611a04c17ba0c435b950ddb9215777)

date-fmt-helper-xz ships a postinstall.js that runs automatically on npm install. The script opens a TCP connection to the hardcoded remote host 8.135.48.40 on port 4444 and pipes /bin/sh stdio over the socket, granting the remote party interactive shell access on the installer's machine. Bash /dev/tcp and python3 pty.spawn fallbacks are included to maximize the chance the shell succeeds across environments. On failure of the shell paths, the script issues an HTTP GET to http://8.135.48.40/shell/failed and /shell/error with the error message, confirming the same host as attacker command-and-control. The package advertises date formatting; the reverse shell is unrelated to any legitimate functionality.

Database specific 
{
    "malicious-packages-origins": [
        {
            "import_time": "2026-08-13T17:24:45.410047058Z",
            "sha256": "b384650ec0fabdd01a7dfc513cccd25156611a04c17ba0c435b950ddb9215777",
            "modified_time": "2026-08-13T17:16:06Z",
            "source": "amazon-inspector",
            "id": "IN-MAL-2026-017637",
            "versions": [
                "1.0.4"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / date-fmt-helper-xz

Package

Name
date-fmt-helper-xz
View open source insights on deps.dev
Purl
pkg:npm/date-fmt-helper-xz

Affected ranges

Affected versions

1.*
1.0.4

Database specific

source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/date-fmt-helper-xz/MAL-2026-13946.json"
indicators 
{
    "evidence_files": [
        {
            "sha256": "6da6821e4a53bdd6c0e40a6f81a0491b98031c5444cf7582b3ec40c08e4718a2",
            "tlsh": "9811ebe905fad07caf7b247866bfa426211342077819eee4b8ce0b03af125680c123a1",
            "path": "postinstall.js"
        }
    ],
    "package_integrity": [
        {
            "filename": "date-fmt-helper-xz-1.0.4.tgz",
            "hashes": {
                "sha1": "2f8c3568222ea92fd0674adfa7ae423bd697a0ee",
                "sha512_sri": "sha512-qbAw4z/0/RbrULoAD8wkNyOylP50WAzItrcYb15Cc8MVW6DW2Ar7lWFS9vkHZTsujZN2w2s1YOYyaNXqxaKp2w=="
            }
        }
    ]
}
cwes 
[
    {
        "name": "Embedded Malicious Code",
        "cweId": "CWE-506",
        "description": "The product contains code that appears to be malicious in nature."
    }
]