Stored XSS through privileged upload of Media Manager file followed by renaming

Winter is a free, open-source content management system. Prior to 1.2.4, users with the `media.manage_media` permission can upload files to the Media Manager and rename them after uploading. Previously, media manager files were only sanitized on upload, not on renaming, which could have allowed a stored XSS attack. This issue has been patched in v1.2.4.