A site developer has experienced issues with Cross-Site Script Inclusion attacks. Which response header could be used to mitigate this attack?

The correct response to mitigate Cross-Site Script Inclusion (XSSI) attacks is to implement the Cross-Origin Resource Policy (CORP) header. This policy helps to control how resources from a web application can be included or fetched from cross-origin domains. By configuring the CORP header properly, the developer can specify which origins are permitted to access certain resources, thereby preventing unauthorized scripts from being executed in the context of the application.

This is essential in mitigating XSSI attacks, as such attacks often involve scripts that are able to leak sensitive data from a site via cross-origin requests. The CORP header can restrict the contexts in which the resources can be embedded, thus adding a layer of security by ensuring that only trusted origins can interact with certain resources.

Other options, while they may be relevant in broader security contexts, do not specifically target the issue of XSSI as effectively as CORP. For instance, while the Cross-Origin Opener Policy (COOP) and Cross-Origin Embedder Policy (COEP) are important for overall cross-origin privacy and security, they do not directly prevent script inclusion vulnerabilities. The X-Frame-Options header, on the other hand, is specifically designed to protect against clickjacking attacks and does not address the concerns related