Firebird is a relational database. Prior to versions 3.0.13, 4.0.6, and 5.0.3, there is an XDR message parsing NULL pointer dereference denial-of-service vulnerability in Firebird. This specific flaw exists within the parsing of xdr message from client. It leads to NULL pointer dereference and DoS. This issue has been patched in versions 3.0.13, 4.0.6, and 5.0.3.
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.