The MHTML protocol handler in Microsoft Outlook Express 5.5 SP2 through Outlook Express 6 SP1 allows remote attackers to bypass domain restrictions and execute arbitrary code, as demonstrated on Internet Explorer using script in a compiled help (CHM) file that references the InfoTech Storage (ITS) protocol handlers such as (1) ms-its, (2) ms-itss, (3) its, or (4) mk:@MSITStore, aka the "MHTML URL Processing Vulnerability."
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A990
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A882
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1028
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1010
https://exchange.xforce.ibmcloud.com/vulnerabilities/15705
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2004/ms04-013
http://www.us-cert.gov/cas/techalerts/TA04-104A.html
http://www.securityfocus.com/bid/9658
http://www.securityfocus.com/bid/9105
http://www.securityfocus.com/archive/1/354447
http://www.kb.cert.org/vuls/id/323070