Typo Security Team reports:
It has been discovered that TYPO3 Core is vulnerable to Cross-Site Scripting and Remote Code Execution. TYPO3 bundles flash files for video and audio playback. Old versions of FlowPlayer and flashmedia are susceptible to Cross-Site Scripting. No authentication is required to exploit this vulnerability. The file upload component and the File Abstraction Layer are failing to check for denied file extensions, which allows authenticated editors (even with limited permissions) to upload php files with arbitrary code, which can then be executed in web server's context.