uploadimg.php in the Automatic Image Upload with Thumbnails (imgUpload) module 1.3.2 for PunBB only verifies the Content-type field of uploaded files, which allows remote attackers to upload and execute arbitrary content via a file with a (1) JPG, (2) GIF, or (3) PNG MIME type.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.