Silverstripe has Cross-site Scripting (XSS) vulnerabilities inherited from TinyMCE

TinyMCE 4.x is vulnerable to several XSS vectors, which had been patched in later versions. Two of these have been identified as affecting silverstripe/admin. Only Silverstripe CMS 4 is affected by this issue. It's not possible to upgrade Silverstripe CMS 4 to use a more recent release of TinyMCE...