Internet Explorer 5.5 and 6 with the Q312461 (MS01-055) patch modifies the HTTP_USER_AGENT (UserAgent) information that indicates that the patch has been installed, which could allow remote malicious web sites to more easily identify and exploit vulnerable clients.

Internet Explorer 5.5 and 6.0 allows remote attackers to read and modify user cookies via Javascript, aka the "Second Cookie Handling Vulnerability."

Internet Explorer 5.5 allows remote attackers to bypass security restrictions via malformed URLs that contain dotless IP addresses, which causes Internet Explorer to process the page in the Intranet Zone, which may have fewer security restrictions, aka the "Zone Spoofing Vulnerability variant" of CVE-2001-0664.

Internet Explorer 5.5 and 5.01 allows remote attackers to bypass security restrictions via malformed URLs that contain dotless IP addresses, which causes Internet Explorer to process the page in the Intranet Zone, which may have fewer security restrictions, aka the "Zone Spoofing vulnerability."

The rendering engine in Internet Explorer determines the MIME type independently of the type that is specified by the server, which allows remote servers to automatically execute script which is placed in a file whose MIME type does not normally support scripting, such as text (.txt), JPEG (.jpg), etc.

Internet Explorer 5.5 does not display the Class ID (CLSID) when it is at the end of the file name, which could allow attackers to trick the user into executing dangerous programs by making it appear that the document is of a safe file type.

Internet Explorer 5.5 and earlier allows remote attackers to obtain the physical location of cached content and open the content in the Local Computer Zone, then use compiled HTML help (.chm) files to execute arbitrary programs.

Internet Explorer 5.5 and earlier does not properly verify the domain of a frame within a browser window, which allows remote web site operators to read certain files on the client by sending information from a local frame to a frame in a different domain, aka a variant of the "Frame Domain Verification" vulnerability.

Internet Explorer 5.5 and earlier does not properly verify the domain of a frame within a browser window, which allows remote web site operators to read certain files on the client by sending information from a local frame to a frame in a different domain using MSScriptControl.ScriptControl and GetObject, aka a variant of the "Frame Domain Verification" vulnerability.

Internet Explorer 5.5 and earlier does not properly validate digital certificates when Certificate Revocation List (CRL) checking is enabled, which could allow remote attackers to spoof trusted web sites, aka the "Server certificate validation vulnerability."