CVE-2019-16377

Vulnerability

Overview

The makandra consul gem, a scope-based authorization solution for Ruby on Rails, contains an incorrect access control vulnerability in versions up to and including 1.0.2 [1]. The flaw arises from improper enforcement of authorization rules defined in Power models, potentially allowing a user to access resources or perform actions that should be restricted [2].

Exploitation

An attacker with a low-privileged account can exploit this vulnerability by crafting requests that bypass the intended authorization checks. The gem's mechanism for defining accessible scopes (e.g., ActiveRecord relations) or boolean powers may not correctly validate the user's permissions in all scenarios, enabling unauthorized access to data or functionality [3]. No authentication bypass is required; the attacker must already have some level of access to the application.

Impact

Successful exploitation could lead to privilege escalation, unauthorized viewing or modification of sensitive data, or access to administrative functions. The exact impact depends on how the application defines its powers, but the vulnerability undermines the core security guarantee of the authorization system.

Mitigation

As of the publication date, no official patch has been released for the consul gem. Users are advised to upgrade to a version beyond 1.0.2 if available, or to review and harden their authorization logic manually. The issue is tracked in the gem's GitHub repository [2] and in the Ruby Advisory Database [3].