MalwarePublished 5 Aug 2026

checkout-test-utils (npm) · Malicious Code

Affects checkout-test-utilsSource GCVE Database

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

Data as of 5 Aug 2026, 16:05 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-12596

What to do

Remove checkout-test-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
npmcheckout-test-utils	Affected =35.1.3	Fixed in–

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Description

The npm package 'checkout-test-utils' version 35.1.3 contains malicious code that automatically downloads and executes attacker-controlled binaries from obfuscated Cloudflare Workers hosts. The package disguises its payload download and execution to evade detection, writing binaries to temporary files and running them without verification. Any user installing or requiring this package will inadvertently execute this malicious code on their host system.

Impact

Any system that installs or requires the affected version of 'checkout-test-utils' will automatically execute attacker-controlled code, potentially leading to full system compromise or further malicious activity. The lack of payload verification and use of obfuscated download methods increases the risk of undetected infection.

Defensive guidance

Users should immediately avoid installing or requiring version 35.1.3 of 'checkout-test-utils'. Remove the package from any affected systems and audit for signs of compromise. Monitor for vendor advisories for updates or official fixes. Due to the nature of the malicious payload execution, reinstalling affected systems may be necessary.

Summary

The 'checkout-test-utils' npm package (version 35.1.3) masquerades as a helper library but its main entry point requires a support script that downloads an opaque binary payload from obfuscated Cloudflare Workers domains. The payload is reconstructed using DNS TXT record fragments from a secondary domain and then saved to the /tmp directory under disguised filenames. The binary is made executable and launched detached via a shell command. No integrity checks are performed on the downloaded payload, and the infrastructure used is not related to the legitimate package publisher. This results in automatic execution of attacker-controlled code on any host that installs or requires this package.

References

npmjs.com/package/checkout-test-utils/v/35.1.3 (opens in a new tab)

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What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Aug 2026, 16:05 UTC

Technical details

References

Community reviews