Description

Security researchers from OX Security have identified three critical vulnerabilities affecting widely used Visual Studio Code extensions, collectively downloaded more than 128 million times. The flaws CVE-2025-65717, CVE-2025-65716, and CVE-2025-65715 impact Live Server, Markdown Preview Enhanced, and Code Runner extensions. These vulnerabilities enable remote file exfiltration, JavaScript execution leading to data theft, and remote code execution. Additionally, Microsoft’s Live Preview extension contained a cross-site scripting (XSS) flaw that could allow full IDE file exfiltration and was quietly patched in version 0.4.16. Because IDE extensions run with elevated privileges, exploitation could expose sensitive data stored on developer machines. The vulnerabilities highlight a systemic risk in the software supply chain: the developer workstation. IDEs contain sensitive assets such as API keys, database credentials, environment variables, and proprietary source code. Malicious or vulnerable extensions can execute code, access files, and communicate over local networks without triggering traditional security alerts. Attackers could exploit Live Server’s localhost functionality to extract files, leverage Markdown Preview Enhanced to scan local ports and exfiltrate data or use Code Runner for remote code execution. Such access could enable lateral movement within corporate networks and compromise organizational systems. Organizations should treat IDE extensions as high-risk components and immediately audit installed extensions, removing those that are unnecessary. Developers must avoid opening untrusted HTML files while localhost servers are active and should not apply configuration snippets from unverified sources. Security teams should enforce extension governance policies, restrict permissions, and monitor developer endpoints for suspicious activity. At a broader level, organizations should implement strict software supply chain controls, maintain updated extensions, and adopt automated scanning and review processes to reduce risk from vulnerable development tools.