BigBlueButton is an open-source virtual classroom. BigBlueButton prior to version 2.6.0-beta.1 has a path traversal vulnerability that allows an attacker with a valid starting folder path, to traverse and read other files without authentication, assuming the files have certain extensions (txt, swf, svg, png). In version 2.6.0-beta.1, input validation was added on the parameters being passed and dangerous characters are stripped. There are no known workarounds.