title: HttpRequestValidationException showing YSOD despite customErrors section
body: <p>we've modified our customErrors section to protect against the recent ASP.NET vulnerability.</p>
  
  <p>Our problem is, that HttpRequestValidationException's are now causing a YSOD's to be shown, other exceptions and page not found errors are showing our custom error page.</p>
  
  <p>If we change the redirectMode to ResponseRedirect everything works fine.</p>
  
  <p>This is our modified section:</p>
  
  <pre><code>&lt;customErrors mode="On" redirectMode="ResponseRewrite" defaultRedirect="~/Error.aspx"/&gt;
  </code></pre>
  
  <p>This question has nothing to do with the recent ASP.NET vulnerability!It's about the ResponseRewrite redirectMode in combination with HttpRequestValidationException's. We know there will soon be a patch and that we could change back to ResponseRedirect.</p>
  
  <p>Kind regards, Martin</p>