rubygem-sprockets before versions 2.12.5, 3.7.2 and 4.0.0beta8 are vulnerable to a path traversal flaw in the sprockets/server.rb:forbiddenrequest?() function. A remote attacker could exploit this to read arbitrary files from the Sprockets server.

External References:

http://www.openwall.com/lists/oss-security/2018/06/19/2 https://blog.heroku.com/rails-asset-pipeline-vulnerability

Upstream Patch:

https://github.com/rails/sprockets/commit/c09131cf5b2c479263939c8582e22b98ed616c5f

Multiple directory traversal vulnerabilities in server.rb in Sprockets before 2.0.5, 2.1.x before 2.1.4, 2.2.x before 2.2.3, 2.3.x before 2.3.3, 2.4.x before 2.4.6, 2.5.x before 2.5.1, 2.6.x and 2.7.x before 2.7.1, 2.8.x before 2.8.3, 2.9.x before 2.9.4, 2.10.x before 2.10.2, 2.11.x before 2.11.3, 2.12.x before 2.12.3, and 3.x before 3.0.0.beta.3, as distributed with Ruby on Rails 3.x and 4.x, allow remote attackers to determine the existence of files outside the application root via a ../ (dot dot slash) sequence with (1) double slashes or (2) URL encoding.