actionview is a conventions and helpers gem for building web pages. Affected versions of this Gem are vulnerable to directory traversal and information leaks. This was meant to be fixed on CVE-2016-0752 but the 3.2 patch was not covering all the scenarios.

Applications that pass unverified user input to the render method in a controller may be vulnerable to an information leak vulnerability.

Impacted code will look something like this:

def index
  render params[:id]
end

Carefully crafted requests can cause the above code to render files from unexpected places like outside the application's view directory, and can possibly escalate this to a remote code execution attack.

All users running an affected release should either upgrade or use one of the workarounds immediately.

A workaround to this issue is to not pass arbitrary user input to the render method. Instead, verify that data before passing it to the render method.

For example, change this:

def index
  render params[:id]
end

To this:

def index
  render verify_template(params[:id])
end

private
def verify_template(name)
add verification logic particular to your application here
end

• http://rubysec.com/advisories/CVE-2016-2097
• https://groups.google.com/forum/#!topic/rubyonrails-security/ddY6HgqB2z4