SSR introduces security risks including a larger attack surface from server-side code execution, race conditions leading to cross-user data leakage, and Server-Side Template Injection (SSTI), all of which are eliminated by SSG's static, pre-built nature.
Static Site Generation (SSG) fundamentally improves security by shifting the workload from request-time server execution to build-time pre-rendering. Since SSG generates all HTML files upfront and serves them as static assets, it removes the dynamic server-side processing layer, thereby eliminating a wide range of attack vectors inherent to Server-Side Rendering (SSR). This architectural difference means that SSG minimizes the attack surface, as there are no live databases, server-side logic, or per-request processing to exploit .
The SSR Risk: SSR requires a live server that executes application code on every request. This creates a large attack surface, and critical vulnerabilities have been discovered in SSR frameworks. For instance, React Server Components (used in Next.js) were found to have vulnerabilities (CVE-2025-55182, CVSS 10.0) that allowed unauthenticated Remote Code Execution (RCE) via malicious HTTP requests . Similarly, SSR introduces risks of Denial of Service (DoS) attacks where an attacker could trigger infinite loops that hang the server (CVE-2025-55184/67779) .
Why SSG Avoids This: SSG completely eliminates this entire class of attack. Because the site is pre-built into static files, there is no server-side rendering logic executing at request time. An attacker cannot send a malicious request to a non-existent server-side rendering function, making RCE and DoS attacks against the rendering engine physically impossible .
The SSR Risk: The SSR process is inherently stateful and concurrent. A recent severe vulnerability in Angular (CVE-2025-59052) demonstrated how a race condition in the SSR dependency injection container could lead to one user's session data (including authentication tokens) being accidentally rendered and sent to another user's browser . This type of vulnerability arises because SSR servers must manage shared state across multiple concurrent requests.
Why SSG Avoids This: SSG has no per-request server-side state. Each user receives the exact same pre-built HTML file from a CDN. There is no server-side logic running concurrently that could mix up user sessions or data, making cross-user data leakage from the rendering engine impossible .
The SSR Risk: SSR often uses templating engines to build HTML. If user input is improperly embedded into a template, it can lead to Server-Side Template Injection (SSTI). An attacker could inject malicious template directives that are executed on the server, leading to Remote Code Execution, information disclosure, or server compromise .
Why SSG Avoids This: With SSG, templates are rendered at build time, not at request time. User input cannot be dynamically fed into the template engine on the server because there is no server to accept the request. The HTML is already built, so SSTI is not a concern.
The SSR Risk: A server performing SSR can be overwhelmed by a high volume of requests, leading to slow responses or complete unavailability. Attackers can exploit expensive-to-render pages to exhaust server resources, causing a Denial of Service .
Why SSG Avoids This: SSG generates static files that are typically served from a Content Delivery Network (CDN). CDNs are designed to handle massive amounts of traffic and are inherently resilient to DoS attacks. By removing the origin server from the critical request path, SSG eliminates the risk of server-side resource exhaustion from high traffic .
- https://owasp.org/www-project-web-security-testing-guide/v41/4-Web_Application_Security_Testing/07-Input_Validation_Testing/18-Testing_for_Server_Side_Template_Injection
- https://www.sanity.io/ssr-vs-ssg-guide#29a1f9d45942
- https://servicestack.net/posts/nextjs-rsc-secure-design
- https://docs.contentisland.net/concepts/ssg-ssr/