CVE-2025-55182, also known as React2Shell, is a critical pre-authentication remote code execution vulnerability affecting React Server Components and related frameworks. The vulnerability also includes CVE-2025-66478, which was merged into the main CVE. This represents a significant security risk as it allows attackers to execute code remotely without authentication. Microsoft has published guidance on defending against this vulnerability. The issue affects React Server Components, which are widely used in modern web applications. Organizations using React-based frameworks should prioritize patching and implementing defensive measures.