The check_connection function in sql_parse.cc in MySQL 4.0.x up to 4.0.26, 4.1.x up to 4.1.18, and 5.0.x up to 5.0.20 allows remote attackers to read portions of memory via a username without a trailing null byte, which causes a buffer over-read.

Buffer overflow in the open_table function in sql_base.cc in MySQL 5.0.x up to 5.0.20 might allow remote attackers to execute arbitrary code via crafted COM_TABLE_DUMP packets with invalid length values.

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.

Stack-based buffer overflow in the init_syms function in MySQL 4.0 before 4.0.25, 4.1 before 4.1.13, and 5.0 before 5.0.7-beta allows remote authenticated users who can create user-defined functions to execute arbitrary code via a long function_name field.

The mysql_create_function function in sql_udf.cc for MySQL 4.0 before 4.0.25, 4.1 before 4.1.13, and 5.0 before 5.0.7-beta, when running on Windows, uses an incomplete blacklist in a directory traversal check, which allows attackers to include arbitrary files via the backslash (\) character.

mysql_install_db in MySQL 4.1.x before 4.1.12 and 5.x up to 5.0.4 creates the mysql_install_db.X file with a predictable filename and insecure permissions, which allows local users to execute arbitrary SQL commands by modifying the file's contents.