Launchpad.net

CVE 2007-0244

pptpgre.c in PoPToP Point to Point Tunneling Server (pptpd) before 1.3.4 allows remote attackers to cause a denial of service (PPTP connection tear-down) via (1) GRE packets with out-of-order sequence numbers or (2) certain GRE packets that are processed using a wrong pointer and improperly dequeued.

See the CVE page on Mitre.org for more details.