Stack-based buffer overflow in the command_Expand_Interpret function in command.c in ppp (aka user-ppp), as distributed in FreeBSD 6.3 and 7.0, OpenBSD 4.1 and 4.2, and the net/userppp package for NetBSD, allows local users to gain privileges via long commands containing "~" characters.
https://exchange.xforce.ibmcloud.com/vulnerabilities/41034
https://euvd.enisa.europa.eu/vulnerability/EUVD-2008-1224
http://www.securityfocus.com/bid/28090
http://www.securityfocus.com/archive/82/489031/30/0/threaded
http://www.securityfocus.com/archive/82/488980/30/0/threaded
http://www.openbsd.org/errata42.html#009_ppp
http://www.openbsd.org/errata41.html#014_ppp
http://secunia.com/advisories/29240