Livewire Remote Code Execution (RCE) on File Uploads

Livewire is a full-stack framework for Laravel that allows for dynamic UI components without leaving PHP. In livewire/livewire prior to 2.12.7 and v3.5.2, the file extension of an uploaded file is guessed based on the MIME type. As a result, the actual file extension from the file name is not validated. An attacker can therefore bypass the validation by uploading a file with a valid MIME type (e.g., image/png) and a “.php” file extension. If the following criteria are met, the attacker can carry out an RCE attack: 1. Filename is composed of the original file name using $file->getClientOriginalName(). 2. Files stored directly on your server in a public storage disk. 3. Webserver is configured to execute “.php” files. This issue has been addressed in release versions 2.12.7 and 3.5.2. All users are advised to upgrade. There are no known workarounds for this vulnerability.