umount in util-linux 2.8 to 2.12q, 2.13-pre1, and 2.13-pre2, and other packages such as loop-aes-utils, allows local users with unmount permissions to gain privileges via the -r (remount) option, which causes the file system to be remounted with just the read-only flag, which effectively clears the nosuid, nodev, and other flags.
marc.info/?l=bugtraq&m=112656096125857&w=2
marc.info/?l=bugtraq&m=112690609622266&w=2
secunia.com/advisories/16785
secunia.com/advisories/16988
secunia.com/advisories/17004
secunia.com/advisories/17027
secunia.com/advisories/17133
secunia.com/advisories/17154
secunia.com/advisories/18502
sunsolve.sun.com/search/document.do?assetkey=1-26-101960-1
support.avaya.com/elmodocs2/security/ASA-2006-014.htm
www.debian.org/security/2005/dsa-823
www.debian.org/security/2005/dsa-825
www.novell.com/linux/security/advisories/2005_21_sr.html
www.osvdb.org/19369
www.securityfocus.com/archive/1/419774/100/0/threaded
www.securityfocus.com/bid/14816
www.ubuntu.com/usn/usn-184-1
exchange.xforce.ibmcloud.com/vulnerabilities/22241
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10921