CVE-2014-1831: Low severity phusion passenger vulnerability

An upstream commit [1] to the Passenger rubygem indicated that versions 4.0.5 and later are affected by a temporary file flaw described as follows:

" Phusion Passenger creates a "server instance directory" in /tmp during startup, which is a temporary directory that Phusion Passenger uses to store working files. This directory is deleted after Phusion Passenger exits. For various technical reasons, this directory must have a semi-predictable filename. If a local attacker can predict this filename, and precreates a symlink with the same filename that points to an arbitrary directory with mode 755, owner root and group root, then the attacker will succeed in making Phusion Passenger write files and create subdirectories inside that target directory. The following files/subdirectories are created:

controlprocess.pid generation-X, where X is a number.

If you happen to have a file inside the target directory called controlprocess.pid, then that file's contents are overwritten.

These files and directories are deleted during Phusion Passenger exit. The target directory itself is not deleted, nor are any other contents inside the target directory, although the symlink is. "

It is fixed in upstream version 4.0.33.

[1] https://github.com/phusion/passenger/commit/34b1087870c2