Treasure your Ruby apps? Protect from unauthorised access immediately

5min read

Image of thief climbing out of laptop shining flashlight on Ruby icon, titled Vulnerability Focus: Ruby.

It’s that time of the week people. Meterian is back with information on a brand new set of vulnerabilities! We once again turn our heads to focus on two Ruby vulnerabilities. The first being found within the Ruby makandra consul gem, and the second being located within the Airbrake Ruby notifier 4.2.3. Both these open-source vulnerabilities are given a 9.8 severity score on NVD, so don’t waste any time –  read up, you could be affected!

  • CVE-2019-16377 The Ruby makandra consul gem for all versions prior to and including 1.0.2 has an Incorrect Access Control vulnerability. This can lead to unauthenticated access to certain controller actions.
  • CVE-2019-16060 The Airbrake Ruby notifier version 4.2.3 mishandles the blacklist_keys configuration option and may therefore may therefore disclose passwords to unauthorized actors.


Vulnerability Score: 9.8

Platform: Ruby

Component: consul gem

Affected Versions: <= 1.0.2

Yes, you heard right. A vulnerability has indeed been detected within the Ruby makandra consul gem for all versions prior to and including 1.0.2. It was discovered by Toby Craze (github id:kratob) on 23/09/19. We are afraid to be the bearer of bad news, but this serious security flaw will affect an unknown function of the component Access Control.

A little context: makandra has been working exclusively with Ruby on Rails since 2007. They are a team of Ruby developers and Linux system engineers based in Germany. Makandra are constantly using open-source software and security patches are applied to the systems they use on a weekly basis. During this time, it has successfully delivered more than 100 Rails projects on more than 90 servers, indicating the amount of users that are at risk of this security flaw. This security issue is located within the consul. For those who don’t know, the consul gem is an authorisation solution for Ruby on Rails and it uses scopes to control what a user can see or edit.

So what is the problem? When a controller has multiple power directives, the ‘:only’ and ‘:except’ of the last directive is applied to all directives. By sending a specially-crafted request, this can lead to an attacker gaining unauthorized access to certain controller actions. With the manipulation of an unknown input, comes a privilege escalation vulnerability. Unfortunately, the impact is negative on confidentiality, integrity and availability. Below is what the affected code would look like.

In this example of code, the powers ‘:foo’ and ‘:bar’ are only checked for the #index action. The other actions were left unprotected by powers checks.

The solution is simple. Upgrade to the latest version of the makandra consul gem (1.0.3. or later), which is available from the consul GIT Repository. or via rubygems. Act fast to get rid of this security bug from your codebases and apps! You could be affected!


Vulnerability Score: 9.8

Platform: Ruby

Component: airbrake-ruby gem

Affected Versions: 4.2.3

Attention Ruby users! The Airbrake Ruby notifier 4.2.3 has mishandled the blacklist_keys configuration option which could result in a very real threat of sensitive data being disclosed to unauthorized actors (e.g password or credentials dumping). What are blacklist_keys? This specifies which keys in the payload should be filtered. Before sending an error, filtered keys will be substituted with the [Filtered] label.

Image of computer, displaying a undisclosed User Name and Password credentials. They are being fished with by a hook. This symbolises the access to sensitive data.
Image from

Airbrake is a plain Ruby notifier gem that is used for integrating apps with Airbrake; it is the leading exception reporting service which provides minimalist API, enabling the notifier to send any Ruby exception to the Airbrake dashboard.  An exception is an event occurring during the execution of a program that disrupts the normal flow of the program’s instructions.  When an uncaught exception occurs, Airbrake could potentially release data to the Airbrake server.

The Airbrake dashboard provides easy categorization, searching, and prioritization of exceptions so that when errors occur, your team can quickly determine the root cause – this allows users to easily review errors, tie an error to an individual piece of code, and trace the cause back to recent changes.

So, what is the problem you say? A data-breach vulnerability–this is due to the mishandling of the blacklist_keys configuration option–within Airbrake Ruby 4.2.3 prevents user data from being filtered prior to sending to Airbrake. In other words, the vulnerability allows a remote attacker to access sensitive information on a targeted system. This compromised data could be user passwords or card payment details, which means an app could leak them  unknowingly; if left untreated, this could very well be the fatal zero-day vulnerability for a business or organization. 

To fix this vulnerability, users must upgrade to 4.2.4 or after. But hurry, as you might be at risk of attackers leaking important confidential data!

That is it for this round folks! Make sure to spread the word on these critically-rated Ruby vulnerabilities in order to help the app sec community defend against unwanted exploits. But as you all know, open-source vulnerabilities are discovered daily, so you can expect us to be back with new vulnerabilities very soon!


Treasure your Ruby apps? Protect from unauthorised access immediately