Image extensions inside product is not working properly

Issue

Steps to reproduce:
1. Navigate to Commerce > Products.
2. Create any simple products.
3. Navigate to media.
4. Take any PDF and change its extension to "png".
5. Make sure png is accepted in the image upload.
Actual Result: The image is getting uploaded.
Expected Result: PDF files should not be allowed. It should check the file's proper type (mime type) and not just the extension.

The observed behavior is a known Liferay DXP bug which has been addressed in Liferay DXP 7.4 Update 82.