xloadimage -- arbitrary command execution when handling compressed files

Tavis Ormandy discovered that xli and xloadimage attempt to
decompress images by piping them through gunzip
or similar decompression tools. Unfortunately, the
unsanitized file name is included as part of the command.
This is dangerous, as in some situations, such as mailcap
processing, an attacker may control the input file name. As a
result, an attacker may be able to cause arbitrary command
execution.