CiviCRM did not properly purify the content of the note fields attached to CiviCase activities when generating Case Reports or viewing the Case Activity
CiviCRM version 5.24.2 and earlier
CiviCRM version 5.24.3 & 5.21.3
Upgrade to the latest CivICRM version
Patrick Figel (Greenpeace CEE) for reporting the issue
Seamus Lee (JMA Consulting/CiviCRM) and Patrick Figel (Greenpeace CEE) for resolving the issue
security/core#40