CVE-2026-105454

RT's automatic link creation for URLs in HTML ticket content does
      not HTML-escape the URL it places in the link. A URL crafted to
      break out of the link's address can add a script that runs when the
      ticket history is displayed, with no further action by the viewer.
      Anyone who can add HTML content to a ticket can plant it. That
      includes an unauthenticated sender of HTML email to any queue that
      grants CreateTicket or ReplyToTicket to Everyone, which is routine
      for a queue that accepts mail from the public. The script runs in
      the session of any user who views the ticket, and can act in RT
      with that user's authority.


This issue was fixed in version 5.0.11 and 6.0.4