title: security message after upgrade to 9.5.17
body: <p>after upgrading to 9.5.17 i get in the reports the following security messages: </p>
  
  <p>Server Response on static files: </p>
  
  <pre><code>www.mydomain.de/typo3temp/assets/43cd7f07.tmp/2500f854.html.wrong
     unexpected content-type text/html
  www.mydomain.de/typo3temp/assets/43cd7f07.tmp/2500f854.1.svg.wrong
     unexpected content-type image/svg+xml
  www.mydomain.de/typo3temp/assets/43cd7f07.tmp/2500f854.php.wrong
     unexpected content PHP content
  www.mydomain.de/typo3temp/assets/43cd7f07.tmp/2500f854.php.txt
     unexpected content PHP content
  </code></pre>
  
  <p>what does this mean? </p>
  
  <p>I inspected the folder /typo3temp/assets/ - there is no folder 43cd7f07.tmp</p>
  
  <p>Thanks!</p>