MalwarePublished 14 Aug 2026

datefmt-core-utils (npm) · Malicious Code

Affects datefmt-core-utilsSource GCVE Database

Malicious package : remove datefmt-core-utils and rotate any secrets on hosts that installed it.

Data as of 14 Aug 2026, 16:52 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-14031

What to do

Remove datefmt-core-utils from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
npmdatefmt-core-utils	Affected =1.0.0	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

The npm package datefmt-core-utils version 1.0.0 contains malicious code in its postinstall script. Upon installation, it opens a TCP connection to a hardcoded remote IP and provides an interactive shell to the attacker, effectively allowing remote code execution. The package's advertised date-formatting functionality is a cover for this backdoor behavior.

Impact

Successful installation of this package version results in remote code execution on the installer's system, providing the attacker with an interactive shell and full control. This compromises the confidentiality, integrity, and availability of the affected system. The malicious code runs with the privileges of the user installing the package.

Defensive guidance

Do not install or use datefmt-core-utils version 1.0.0. Remove any installations of this package immediately. Monitor for any unauthorized access resulting from this compromise.

Summary

The datefmt-core-utils npm package (version 1.0.0) includes a postinstall.js script that executes automatically during installation. This script establishes a TCP connection to the remote IP 8.135.48.40 on port 4444 and redirects the local /bin/bash shell's input and output streams to this socket. It attempts three methods to spawn an interactive shell (using python3 pty.spawn, python3 subprocess, and Node.js net combined with child_process.spawn). This behavior effectively grants the remote endpoint full shell access on the installer's machine. The legitimate date-formatting code in index.js is a decoy to hide the malicious payload.

References

npmjs.com/package/datefmt-core-utils/v/1.0.0 (opens in a new tab)

Community reviews

Loading reviews…

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Aug 2026, 16:52 UTC

Technical details

References

Community reviews