Drupal 8.4.x versions before 8.4.5 and Drupal 7.x versions before 7.57 has
a Drupal.checkPlain() JavaScript function which is used to escape
potentially dangerous text before outputting it to HTML (as JavaScript
output does not typically go through Twig autoescaping). This function does
not correctly handle all methods of injecting malicious HTML, leading to a
cross-site scripting vulnerability under certain circumstances. The PHP
functions which Drupal provides for HTML escaping are not affected.
Upstream:released (7.57-1)
Ubuntu 12.04 ESM (Precise Pangolin):DNE
Ubuntu 14.04 ESM (Trusty Tahr):DNE (trusty was needed)
Ubuntu 16.04 LTS (Xenial Xerus):needed
Ubuntu 18.04 LTS (Bionic Beaver):DNE
Ubuntu 19.04 (Disco Dingo):DNE
Ubuntu 19.10 (Eoan):DNE
More Information

Updated: 2019-09-19 14:40:00 UTC (commit d32ebc32606b9517c6fa7d65a15441e2a57a6de5)