The Web Workers implementation in Microsoft Internet Explorer 10 and 11 and Microsoft Edge allows remote attackers to bypass the Same Origin Policy via unspecified vectors, aka "Microsoft Browser Security Feature Bypass Vulnerability."
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-145
https://docs.microsoft.com/en-us/security-updates/securitybulletins/2016/ms16-144