Stored XSS via Structure entry title in table view

Summary

An Author-level control panel user can store a JavaScript payload in an entry title. When an admin, or any control panel user with saveEntries for the same Structure section, drags another entry under the poisoned entry in table view, the payload executes in the victim’s session.

The issue is exploitable because the title is escaped into data-title by the server, decoded again by the browser, read with jQuery .data('title'), and then concatenated into a new HTML string without attribute escaping.

Execution was verified with alert(document.domain). Impact was verified against an elevated admin session by changing the admin user’s email through users/save-user, then using the password-reset flow to take over the account.

Preconditions

• Attacker has createEntries + saveEntries on a Structure-type section (Author-style CP account; no admin permission required).
• Victim has saveEntries on the same section. Craft only renders drag handles when structureEditable is true, which requires this permission, so any admin qualifies.
• Section must be type Structure. Channel and Single sections are unaffected.
• Poisoned entry must have no children at the time of the drag (fires on the 0-to-1 descendant transition).
• For the email-change account-takeover path, the victim must currently have an elevated session. The stored XSS itself does not require elevation.

Root cause

ElementTableSorter.js lines 643-652:

const ancestorTitle = this._updateAncestors._$ancestor.data('title');
$(
  '<button … aria-label="' +
    Craft.t('app', 'Show {title} children', {title: ancestorTitle}) +
  '"></button>'
).insertAfter(…);

Craft.t with a {title} token calls _parseToken, reaches case 'none': return arg (Craft.js:193-194), and returns the title verbatim. The result is handed to jQuery's $() and parsed as HTML.