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.

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 4.0.23 and earlier, and 4.1.x up to 4.1.10, uses predictable file names when creating temporary tables, which allows local users with CREATE TEMPORARY TABLE privileges to overwrite arbitrary files via a symlink attack.

MySQL 4.0.23 and earlier, and 4.1.x up to 4.1.10, allows remote authenticated users with INSERT and DELETE privileges to bypass library path restrictions and execute arbitrary libraries by using INSERT INTO to modify the mysql.func table, which is processed by the udf_init function.

MySQL 4.0.23 and earlier, and 4.1.x up to 4.1.10, allows remote authenticated users with INSERT and DELETE privileges to execute arbitrary code by using CREATE FUNCTION to access libc calls, as demonstrated by using strcat, on_exit, and exit.

Stack-based buffer overflow in MySQL 4.1.x before 4.1.3, and 5.0, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long scramble string.

The check_scramble_323 function in MySQL 4.1.x before 4.1.3, and 5.0, allows remote attackers to bypass authentication via a zero-length scrambled string.

MySQL 4.x before 4.0.21, and 3.x before 3.23.49, allows attackers to cause a denial of service (crash or hang) via multiple threads that simultaneously alter MERGE table UNIONs.