Internet Explorer 4.x and 5.x does not properly re-validate an SSL certificate if the user establishes a new SSL session with the same server during the same Internet Explorer session, aka one of two different "SSL Certificate Validation" vulnerabilities.
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.
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.