Severity Rating: Critical
Revision Note: V1.1 (December 16, 2015): Bulletin revised to further clarify the steps users must take to be protected from the vulnerability described in CVE-2015-6161. This bulletin, MS15-124, provides protections for this issue, but user action is required to enable them; the cumulative update for Internet Explorer does not enable the protections by default. Before applying the protections, Microsoft recommends that customers perform testing appropriate to their environment and system configurations.