Sudo before 1.6.6 contains an off-by-one error that can result in a heap-based buffer overflow that may allow local users to gain root privileges via special characters in the -p (prompt) argument, which are not properly expanded.
http://www.kb.cert.org/vuls/id/820083
http://marc.info/?l=bugtraq&m=102010164413135&w=2
http://marc.info/?l=bugtraq&m=101979472822196&w=2