The extension parser in slp_v2message.c in OpenSLP 1.2.1, and other versions before SVN revision 1647, as used in Service Location Protocol daemon (SLPD) in VMware ESX 4.0 and 4.1 and ESXi 4.0 and 4.1, allows remote attackers to cause a denial of service (infinite loop) via a packet with a "next extension offset" that references this extension or a previous extension.  NOTE: some of these details are obtained from third party information.