Microsoft Internet Explorer 6.0.2900.2180 and earlier allows remote attackers to cause a denial of service (CPU and memory consumption) via a long Unicode string argument to the write method, a related issue to CVE-2009-2479. NOTE: it was later reported that 7.0.6000.16473 and earlier are also affected.
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.
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.