Firebird is an open-source relational database management system. In versions prior to 6.0.0, 5.0.4, 4.0.7 and 3.0.14, when processing an op_slice network packet, the server passes an unprepared structure containing a null pointer to the SDL_info() function, resulting in a null pointer dereference and server crash. An unauthenticated attacker can trigger this by sending a crafted packet to the server port. This issue has been fixed in versions 6.0.0, 5.0.4, 4.0.7 and 3.0.14.