Critical Malicious Code Vulnerability in sinon-node Package

sinon-node Updated 11 Feb 2026

Summary

11/02/2026

Disclosed on

CRITICAL

Severity

No i

Fix available

Critical

Severity

Not published

CVSS Score

MAL-2026-854: Malicious code in sinon-node (npm). Affected versions are not published. No fix is published. How to fix ↓

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Background

Sinon-node is a popular JavaScript library used for creating spies, mocks, and stubs in testing environments. It is widely utilized in Node.js applications to facilitate unit testing by allowing developers to replace real functions with controlled implementations. However, the sinon-node package has been compromised, leading to a severe security vulnerability that can fully compromise any system where it is installed.

Vulnerability Detail

The vulnerability stems from the presence of malicious code embedded within the sinon-node package. This code can grant unauthorized access to an attacker, allowing them to control the affected system completely. As a result, any secrets or sensitive information stored on the compromised machine may be exposed. The malicious code was identified in the package's source, and it is crucial for users to recognize that simply removing the package may not eliminate all traces of the malware.

How To Fix

This package is malicious. Remove it and rotate any credentials it could have accessed.

npm uninstall sinon-node

If it arrived as a transitive dependency, remove the package that pulled it in, then reinstall.

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Workaround

As a temporary workaround, you can isolate your application from the compromised package by using a different testing library or framework until the issue is resolved. For example, consider using Jest or Mocha for your testing needs.

Conclusion

The sinon-node package has been compromised with malicious code, posing a significant risk to any system where it is installed. Immediate action is required to remove the package and secure any exposed information. Users should stay vigilant and consider alternative testing libraries until a safe version is available.

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