CVE-2013-4299 (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2013-4299): Interpretation conflict in drivers/md/dm-snap-persistent.c in the Linux kernel through 3.11.6 allows remote authenticated users to obtain sensitive information or modify data via a crafted mapping to a snapshot block device.
Fixed in 3.12: https://github.com/torvalds/linux/commit/e9c6a182649f4259db704ae15a91ac820e63b0ca