The RegEx class in the XSS filter in Microsoft Internet Explorer 9 through 11 and Microsoft Edge allows remote attackers to conduct cross-site scripting (XSS) attacks and obtain sensitive information via unspecified vectors, aka "Microsoft Browser Information Disclosure Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-142
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-129