Simon Kilvington discovered that specially crafted PNG images can trigger a heap overflow in libavcodec, the multimedia library of ffmpeg, which may lead to the execution of arbitrary code.
The old stable distribution (woody) doesn't contain ffmpeg packages.
For the stable distribution (sarge) this problem has been fixed in version 0.cvs20050313-2sarge1.
For the unstable distribution (sid) this problem has been fixed in version 0.cvs20050918-5.1.
We recommend that you upgrade your ffmpeg package.