The default configuration of Firebird before 2.0.3.12981.0-r6 on Gentoo Linux sets the ISC_PASSWORD environment variable before starting Firebird, which allows remote attackers to bypass SYSDBA authentication and obtain sensitive database information via an empty password.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42299
http://www.securityfocus.com/bid/29123
http://security.gentoo.org/glsa/glsa-200805-06.xml