Ethereal developers discovered a buffer overflow in the ISIS protocol dissector. It may be possible to make Ethereal crash or hang by injecting a purposefully malformed packet onto the wire, or by convincing someone to read a malformed packet trace file. It may be possible to make Ethereal run arbitrary code by exploiting the buffer and pointer problems.
This problem has been fixed in version 0.9.4-1woody2 for the current stable distribution (woody), in version 0.8.0-4potato.1 for the old stable distribution (potato) and in version 0.9.6-1 for the unstable distribution (sid).
We recommend that you upgrade your ethereal packages.