PGP Desktop before 9.5.1 does not validate data objects received over the (1) \pipe\pgpserv named pipe for PGPServ.exe or the (2) \pipe\pgpsdkserv named pipe for PGPsdkServ.exe, which allows remote authenticated users to gain privileges by sending a data object representing an absolute pointer, which causes code execution at the corresponding address.
http://www.vupen.com/english/advisories/2007/0356
http://www.securityfocus.com/bid/22247
http://www.securityfocus.com/archive/1/458137/100/0/threaded
http://www.ngssoftware.com/advisories/medium-risk-vulnerability-in-pgp-desktop/
http://www.kb.cert.org/vuls/id/102465
http://securitytracker.com/id?1017563
http://securityreason.com/securityalert/2203
http://secunia.com/advisories/23938
http://archives.neohapsis.com/archives/vulnwatch/2007-q1/0025.html