client/mount.cifs.c in mount.cifs in smbfs in Samba 3.4.5 and earlier does not verify that the (1) device name and (2) mountpoint strings are composed of valid characters, which allows local users to cause a denial of service (mtab corruption) via a crafted string.
http://www.vupen.com/english/advisories/2010/1062
http://www.securityfocus.com/bid/38326
http://www.mandriva.com/security/advisories?name=MDVSA-2010:090
http://security.gentoo.org/glsa/glsa-201206-29.xml
http://secunia.com/advisories/39317
http://lists.opensuse.org/opensuse-security-announce/2010-08/msg00001.html
http://lists.opensuse.org/opensuse-security-announce/2010-04/msg00001.html
http://git.samba.org/?p=samba.git%3Ba=commit%3Bh=a065c177dfc8f968775593ba00dffafeebb2e054