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Phusion Passenger 4.0.37 released

By Hongli Lai on January 29th, 2014

Phusion Passenger is a fast and robust web server and application server for Ruby, Python, Node.js and Meteor. Passenger takes a lot of complexity out of deploying web apps, and adds powerful enterprise-grade features that are useful in production. High-profile companies such as Apple, New York Times, AirBnB, Juniper, American Express, etc are already using it, as well as over 350.000 websites.

Phusion Passenger is under constant maintenance and development. Version 4.0.37 is a bugfix release.

Phusion Passenger also has an Enterprise version which comes with a wide array of additional features. By buying Phusion Passenger Enterprise you will directly sponsor the development of the open source version.

Recent changes

  • Improved Node.js compatibility. Calling on() on the request object now returns the request object itself. This fixes some issues with Express, Connect and Formidable. Furthermore, some WebSocket-related issues have been fixed.
  • Improved Meteor support. Meteor application processes are now shut down quicker. Previously, they linger around for 5 seconds while waiting for all connections to terminate, but that didn’t work well because WebSocket connections were kept open indefinitely. Also, some WebSocket-related issues have been fixed.
  • Introduced a new tool `passenger-config detach-process` for gracefully detaching an application process from the process pool. Has a similar effect to killing the application process directly with `kill <PID>`, but killing directly may cause the HTTP client to see an error, while using this command guarantees that clients see no errors.
  • Fixed a crash that occurs when an application fails to spawn, but the HTTP client disconnects before the error page is generated. Fixes issue #1028.
  • Fixed a symlink-related security vulnerability.

    Urgency: low
    Scope: local exploit
    Summary: writing files to arbitrary directory by hijacking temp directories
    Affected versions: 4.0.5 and later
    Fixed versions: 4.0.37

    Description: 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:

    • generation-X, where X is a number.

    If you happen to have a file inside the target directory called ``, 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.

    Thanks go to Jakub Wilk for discovering this issue.

Installing or upgrading to 4.0.37

OS X OS X Debian Debian Ubuntu Ubuntu
Heroku Heroku Ruby gem Ruby gem Tarball Tarball


Phusion Passenger’s core is open source. Please fork or watch us on Github. 🙂

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