UNIX Symbolic Link (Symlink) Following
Phusion Passenger before 4.0.37 allows local users to write to certain files and directories via a symlink attack on "control_process.pid" or a "generation-*" file.
CWE-61 - UNIX Symbolic Link (Symlink) Following
The software, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the software to operate on unauthorized files.