The MITRE CVE dictionary describes this issue as:
MySQL 5.0.18 and earlier allows local users to bypass logging mechanisms via SQL queries that contain the NULL character, which are not properly handled by the mysql_real_query function. NOTE: this issue was originally reported for the mysql_query function, but the vendor states that since mysql_query expects a null character, this is not an issue for mysql_query.
Find out more about CVE-2006-0903 from the
MITRE CVE dictionary dictionary and