actionview is a conventions and helpers gem for building web pages. Affected versions of this Gem are vulnerable to directory traversal and information leaks.

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-2016-0752
• https://groups.google.com/forum/#!topic/rubyonrails-security/335P1DcLG00