administrator/components/com_media/helpers/media.php in the media manager in Joomla! 2.5.x before 2.5.14 and 3.x before 3.1.5 allows remote authenticated users or remote attackers to bypass intended access restrictions and upload files with dangerous extensions via a filename with a trailing . (dot), as exploited in the wild in August 2013.
developer.joomla.org/security/563-20130801-core-unauthorised-uploads.html
joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31626
seclists.org/oss-sec/2013/q3/484
seclists.org/oss-sec/2013/q3/486
www.cso.com.au/article/523528/joomla_patches_file_manager_vulnerability_responsible_hijacked_websites/
www.exploit-db.com/exploits/27610
www.kb.cert.org/vuls/id/639620
github.com/joomla/joomla-cms/commit/1ed07e257a2c0794ba19e864f7c5101e7e8c41d2
github.com/joomla/joomla-cms/commit/fa5645208eefd70f521cd2e4d53d5378622133d8