TYPO3 Core

$TYPO3_CONF_VARS['GFX']['imagefile_ext'] is used to limit the allowed files for image handling. It is used too restrictive. Images which are included via TS are also not handled which is leading to the following major problem:

If set to 'png' and using TS to include a jpg file, the image dimensions are not calculated, leading to the attributes width="" and height="" or even not rendering the image itself.

IMO removing the checks is the best solution as imagefile_ext is used in tceforms anyway to prohibit editors to use not allowed image files.

How to test:
1.) Set $TYPO3_CONF_VARS['GFX']['imagefile_ext'] = 'png';
2.) Use a TS like
----
page.10 = IMAGE
page.10.file = fileadmin/dummy.jpg
-----
3.) See the wrong output
4.) Apply patch and recheck.
(issue imported from #M15278)