A Microsoft ActiveX control allows a remote attacker to execute a malicious cabinet file via an attachment and an embedded script in an HTML mail, aka the "Active Setup Control" vulnerability.
The Microsoft virtual machine (VM) in Internet Explorer 4.x and 5.x allows a remote attacker to read files via a malicious Java applet that escapes the Java sandbox, aka the "VM File Reading" vulnerability.
Microsoft Internet Explorer 4.0 through 6.0 could allow local users to differentiate between alphanumeric and non-alphanumeric characters used in a password by pressing certain control keys that jump between non-alphanumeric characters, which makes it easier to conduct a brute-force password guessing attack.