Ethereal 0.9.7 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via malformed packets to the (1) LMP, (2) PPP, or (3) TDS dissectors, possibly related to a missing field for EndVerifyAck messages.
http://www.redhat.com/support/errata/RHSA-2002-290.html
http://www.ethereal.com/cgi-bin/viewcvs.cgi/ethereal/packet-lmp.c#rev1.13