How a Single Malicious Commit Can Compromise a Vite-React-TypeScript App

A security analysis explores what happens when a malicious commit reaches production in a Vite, React, and TypeScript frontend application. Once hostile JavaScript is deployed, it runs under the site's origin in every affected visitor's browser, giving it the same privileges as the legitimate app — enabling keystroke capture, storage access, API calls, and data exfiltration. Beyond the browser, malicious repository code can also execute during CI/CD build steps, potentially exposing secrets, cloud credentials, and deployment tokens through npm lifecycle hooks. The research outlines a tiered threat model ranging from read-only repository access to full backend compromise, depending on CI permissions and API security. The findings serve as a threat-modeling and audit guide for frontend teams to assess and reduce their supply-chain exposure.