From NVD
Microsoft Internet Explorer 5.01 SP4, 6, 6 SP1, 7, and 8 does not prevent rendering of non-HTML local files as HTML documents, which allows remote attackers to bypass intended access restrictions and read arbitrary files via vectors involving JavaScript exploit code that constructs a reference to a file://127.0.0.1 URL, aka the dynamic OBJECT tag vulnerability, as demonstrated by obtaining the data from an index.dat file, a variant of CVE-2009-1140 and related to CVE-2008-1448.