Thomas Goirand uploaded new packages for horizon which fixed the
following security problem:

  Sunil Yadav from IBM Security Services reported a persistent XSS in
  Horizon. An authenticated user may conduct a persistent XSS attack by
  setting a malicious metadata to a Glance image, a Nova flavor or a
  Host Aggregate and tricking an administrator to load the update
  metadata page. Once executed in a legitimate context this attack may
  result in a privilege escalation.

For the jessie-backports distribution the problems have been fixed in