<p>Servers <a href="#cors-server">disable all cross-origin protections</a> in browsers because resource access is governed explicitly by <a href="#web-access-control">Web Access Control</a>. As such, servers cannot rely on browser-based cross-origin protection mechanisms for determining the authentication status or representation of a resource. In particular, servers are strongly encouraged to ignore HTTP cookies from untrusted origins. Additional security measures can be taken to prevent metadata in error responses from leaking. For instance, a malicious application could probe multiple servers to check whether the response status code is <code>401</code> or <code>403</code>, or could try to access an error page from an intranet server within the user agent’s private network to extract company names or other data. To mitigate this, when a request from an untrusted <code>Origin</code> arrives, the server may want to set the status code of error responses to <code>404</code> and/or anonymize or censor their contents.</p>
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