UNIX Symbolic Link (Symlink) Following
Phusion Passenger 4.0.37 allows local users to write to certain files and directories via a symlink attack on (1) "control_process.pid" or a (2) "generation-*" file. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-1831.
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.