ffmpeg -- 4xm processing memory corruption vulnerability

Secunia reports:

Tobias Klein has reported a vulnerability in FFmpeg, which
potentially can be exploited by malicious people to compromise an
application using the library.
The vulnerability is caused due to a signedness error within the
“fourxm_read_header()” function in libavformat/4xm.c. This can be
exploited to corrupt arbitrary memory via a specially crafted 4xm
file.