MalwarePublished 13 Jul 2026

dotnet-runtime-base (npm) · Malicious Code

Affects dotnet-runtime-baseSource GCVE Database

Malicious package : remove dotnet-runtime-base and rotate any secrets on hosts that installed it.

Data as of 13 Jul 2026, 09:52 UTC

Classification

Malicious package

Published to npm · OSV MAL-2026-10217

What to do

Remove dotnet-runtime-base 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
npmdotnet-runtime-base	Affected =1.0.5 =1.0.4	Fixed in–

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Description

The npm package dotnet-runtime-base versions 1.0.4 and 1.0.5 contains malicious code in its postinstall script. On Windows systems, the script downloads and executes an attacker-controlled binary from a personal GitHub repository, running it hidden with bypassed execution policies. This behavior results in arbitrary code execution on the installer's machine and likely full system compromise. The malicious payload is designed to evade detection in development and CI environments. Removal of the package does not guarantee elimination of all malicious artifacts. Immediate secret and key rotation is recommended if the package was installed.

Impact

Installing the affected versions of dotnet-runtime-base on Windows leads to arbitrary code execution by downloading and running a hidden attacker-controlled executable. This compromises the entire system, potentially exposing all stored secrets and keys. The attacker gains full control over the compromised machine. Removal of the package alone may not remove all malicious components, indicating persistent compromise.

Defensive guidance

Users should immediately remove the dotnet-runtime-base package versions 1.0.4 and 1.0.5 if installed. Due to the high likelihood of full system compromise, all secrets and keys stored on the affected machine should be rotated from a separate, trusted device. Monitor for any suspicious activity and consider rebuilding the affected system to ensure complete remediation.

Summary

The dotnet-runtime-base npm package versions 1.0.4 and 1.0.5 include a postinstall lifecycle script that executes install.js. On Windows, this script writes a PowerShell script to the temporary directory and uses WebClient.DownloadFile to fetch an executable from an unrelated personal GitHub account's mutable branch. The executable is launched with hidden window style and bypassed execution policy, enabling arbitrary attacker-controlled code execution. The payload avoids running in non-Windows environments and when NODE_ENV is set to 'development', evading developer and CI detection. The lack of hash or signature verification on the downloaded binary increases risk. This results in a fully compromised system upon installation.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Jul 2026, 09:52 UTC

Technical details

References

Community reviews