A memory leak was found in the libpng processed malformed Portable Network
Graphics (PNG) images with Physical Scale (sCAL) extension. A remote attacker
could create a specially-crafted PNG image and trick the local user into
opening it in an application, using the libpng library, leading to denial
of service (relevant libpng-based application crash).

References:
  [1] http://www.libpng.org/pub/png/libpng.html