The png_handle_sCAL function in pngrutil.c in libpng 1.0.x before 1.0.55, 1.2.x before 1.2.45, 1.4.x before 1.4.8, and 1.5.x before 1.5.4 does not properly handle invalid sCAL chunks, which allows remote attackers to cause a denial of service (memory corruption and application crash) or possibly have unspecified other impact via a crafted PNG image that triggers the reading of uninitialized memory.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.