The get_dataroot_image_path function in lib/file.php in Mahara before 1.4.1 does not properly validate uploaded image files, which allows remote attackers to cause a denial of service (memory consumption) via a (1) large or (2) invalid image.
https://launchpad.net/mahara/+milestone/1.4.1
https://bugs.launchpad.net/mahara/+bug/784978