Kallithea, a member project of Software Freedom Conservancy, is a GPLv3'd, Free Software source code management system that supports two leading version control systems, Mercurial and Git, and has a web interface that is easy to use for users and admins.
Kallithea suffers from a HTTP header injection (response splitting) vulnerability because it fails to properly sanitize user input before using it as an HTTP header value via the GET 'came_from' parameter in the login instance. This type of attack not only allows a malicious user to control the remaining headers and body of the response the application intends to send, but also allow them to create additional responses entirely under their control.