CKEditor, a third-party JavaScript library included in Drupal core, has fixed a cross-site scripting (XSS) vulnerability. The vulnerability stemmed from the fact that it was possible to execute XSS inside CKEditor when using the image2 plugin (which Drupal 8 core also uses).

We would like to thank the CKEditor team for patching the vulnerability and coordinating the fix and release process, and matching the Drupal core security window.