TraceManager in Firebird 2.5.0 and 2.5.1, when trace is enabled, allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) by preparing an empty dynamic SQL query.
https://exchange.xforce.ibmcloud.com/vulnerabilities/80073
http://www.securitytracker.com/id?1027769
http://www.securityfocus.com/bid/56521
http://www.openwall.com/lists/oss-security/2012/11/14/8
http://www.openwall.com/lists/oss-security/2012/11/14/6