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.
The mysqlhotcopy script in mysql 4.0.20 and earlier, when using the scp method from the mysql-server package, allows local users to overwrite arbitrary files via a symlink attack on temporary files.
MySQL 3.20 through 4.1.0 uses a weak algorithm for hashed passwords, which makes it easier for attackers to decrypt the password via brute force methods.
Buffer overflow in MySQL daemon (mysqld) before 3.23.50, and 4.0 beta before 4.02, on the Win32 platform, allows local users to execute arbitrary code via a long "datadir" parameter in the my.ini initialization file, whose permissions on Windows allow Full Control to the Everyone group.
Directory traversal vulnerability in MySQL before 3.23.36 allows local users to modify arbitrary files and gain privileges by creating a database whose name starts with .. (dot dot).
MySQL before 3.23.31 allows users with a MySQL account to use the SHOW GRANTS command to obtain the encrypted administrator password from the mysql.user table and possibly gain privileges via password cracking.