source: http://www.securityfocus.com/bid/17733/info

Applications using the LibTIFF library are prone to a double-free vulnerability; a fix is available.

Attackers may be able to exploit this issue to cause denial-of-service conditions in affected applications using a vulnerable version of the library; arbitrary code execution may also be possible.

http://www.exploit-db.com/sploits/27765.tiff.2