MalwarePublished 5 Aug 2026

checkout-storage-service (npm) · Malicious Code

Affects checkout-storage-serviceSource GCVE Database

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

Data as of 5 Aug 2026, 16:02 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-12592

What to do

Remove checkout-storage-service 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-storage-service	Affected =35.2.9	Fixed in–

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Description

The npm package 'checkout-storage-service' version 35.2.9 contains malicious code that downloads and executes opaque payloads from anonymous Cloudflare Workers domains. The payload is saved to hidden files on the host system and executed with elevated permissions, using evasion techniques such as split string assembly, throttling execution, and suppressing error logs. This behavior is designed to blend into normal system activity and evade static analysis.

Impact

This malicious package can execute arbitrary code on the host system by downloading and running opaque payloads, potentially leading to system compromise, data theft, or persistence. The use of covert channels and evasion techniques complicates detection and response. Since the payload is opaque and dynamically fetched, the exact impact depends on the downloaded code but poses a high risk to affected systems.

Defensive guidance

Users should immediately remove version 35.2.9 of 'checkout-storage-service' from their environments and avoid installing it. Verify the integrity of dependencies and consider using trusted package sources or lockfiles to prevent supply chain attacks. Monitor for any suspicious activity related to this package and update to a safe version if one becomes available.

Summary

The 'checkout-storage-service' npm package version 35.2.9 includes a malicious component in _helpers.js that selects platform-specific endpoints and downloads executable payloads over HTTPS from a rotating list of Cloudflare Workers subdomains. It also uses a DNS-TXT covert channel fallback via several suspicious domains. The downloaded payload is saved as a hidden file in /tmp on Unix or as a disguised executable on Windows, then executed detached from the main process. The code employs evasion techniques such as assembling host strings from split arrays to avoid detection, throttling execution via TTL flag files and environment variable checks mimicking opt-out telemetry, and silencing stderr output. The payload origin is unrelated to the package publisher, indicating a supply chain compromise or malicious package insertion.

References

npmjs.com/package/checkout-storage-service/v/35.2.9 (opens in a new tab)

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What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Aug 2026, 16:02 UTC

Technical details

References

Community reviews