The in_decimal::set function in item_cmpfunc.cc in MySQL before 5.0.40, and 5.1 before 5.1.18-beta, allows context-dependent attackers to cause a denial of service (crash) via a crafted IF clause that results in a divide-by-zero error and a NULL pointer dereference.

MySQL before 4.1.21, 5.0 before 5.0.25, and 5.1 before 5.1.12, when run on case-sensitive filesystems, allows remote authenticated users to create or access a database when the database name differs only in case from a database for which they have permissions.

Off-by-one buffer overflow in the Instance_options::complete_initialization function in instance_options.cc in the Instance Manager in MySQL before 5.0.23 and 5.1 before 5.1.12 might allow local users to cause a denial of service (application crash) via unspecified vectors, which triggers the overflow when the convert_dirname function is called. NOTE: the vendor has disputed this issue via e-mail to CVE, saying that it is only exploitable when the user has access to the configuration file or the Instance Manager daemon. Due to intended functionality, this level of access would already allow the user to disrupt program operation, so this does not cross security boundaries and is not a vulnerability