Published:2007/06/18  Last Updated:2008/05/21

Internet Explorer vulnerable in handling MHTML protocol


Internet Explorer is vulnerable in handling MHTML (MIME Encapsulation of Aggregate HTML) protocol, which allows the download dialog box to be bypassed.

Products Affected

Some versions of Outlook Express are affected because the vulnerability is contained in Outlook Express component used by Internet Explorer.

  • Outlook Express 6
    Windows XP / Windows Server 2003
  • Windows Mail
    Windows Vista


When Internet Explorer accesses a website using MHTML (MIME Encapsulation of Aggregate HTML), Internet Explorer processes the contents as MHTML data, ignoring their actual content types, and it does not properly handle the Content-Disposition header field. This could cause a dialog box not to be displayed when downloading.
The MHTML protocol handler is included in Outlook Express component, and Microsoft provides the fix for this componet.


An arbitrary script could be executed without explicit user consent, as the download dialog box is not displayed on the user's IE.


Update the Software
Apply the updates provided by the vendor.

For more information, refer to the vendor's website.


JPCERT/CC Addendum

Vulnerability Analysis by JPCERT/CC

Analyzed on 2007.06.18

Measures Conditions Severity
Access Required Routed - can be attacked over the Internet using packets
  • High
Authentication None - anonymous or no authentication (IP addresses do not count)
  • High
User Interaction Required Simple - the user must be convinced to take a standard action that does not feel harmful to most users, such as click on a link or view a file
  • Medium
Exploit Complexity Low - little to no expertise and/or luck required to exploit (cross-site scripting)
  • High

Description of each analysis measures


HASEGAWA, Yosuke of reported this vulnerability to IPA.
JPCERT/CC coordinated with the vendors under Information Security Early Warning Partnership.

Other Information

JPCERT Alert JPCERT-AT-2007-0014
JPCERT Reports
CERT Advisory Technical Cyber Security Alert TA07-163A
CPNI Advisory
CVE CVE-2007-2227
JVN iPedia JVNDB-2007-000447

Update History