Key Information Vulnerability Overview CVE ID: CVE-2016-7954 Affected Scope: All stable versions of Bundler Vulnerability Description: Attackers can inject arbitrary code through any secondary gem sources declared in the Gemfile, regardless of whether the source is restricted to specific gems. Example Source Ambiguity Warning Issue: When a gem can be installed from multiple sources, Bundler displays a warning advising users to restrict the gem's source. Solution: Use the option or source blocks. Option Attempt using option: Actual Effect: All three gems are installed from the secondary source. Source Blocks Using source blocks: Actual Effect: Still fails to resolve the source ambiguity issue. Mitigation Measures Use Multiple Source Blocks: Currently, the only way to ensure gems are installed from the intended source is to place each gem declaration within its own source block. Fixing Bundler Report Date: April 1, 2016 Fix Status: Patched in Bundler 2 development, but not planned to be backported to Bundler 1 due to required backward-incompatible changes.