added sanity check for images in is_allowed_filetype() using getimagesize()
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index c66ff23..cb9a370 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -95,6 +95,7 @@
<li>Added 'application/msexcel' to config/mimes.php for .xls files.</li>
<li>Added 'proxy_ips' config item to whitelist reverse proxy servers from which to trust the HTTP_X_FORWARDED_FOR header to
to determine the visitor's IP address.</li>
+ <li>Improved accuracy of Upload::is_allowed_filetype() for images (#6715)</li>
</ul>
</li>
</ul>