png -- libpng decompression denial of service

A vulnerability in libpng can result in denial of service
conditions when a remote attacker tricks a victim to open
a specially-crafted PNG file.
The PNG project describes the problem in an advisory:

Because of the efficient compression method used in
Portable Network Graphics (PNG) files, a small PNG file
can expand tremendously, acting as a “decompression
bomb”.
Malformed PNG chunks can consume a large amount of CPU
and wall-clock time and large amounts of memory, up to
all memory available on a system