Since 2005, Bishop Fox has provided security consulting services to the Fortune 1000, high-tech startups, and financial institutions worldwide. The author of Beast, Vinnie Falco, engaged Bishop Fox to assess the security of the Boost C++ Beast HTTP/S networking library. The following report details the findings identified during the course of the engagement, which started on September 11, 2017. The assessment team conducted a hybrid application assessment of the Beast library. Bishop Fox’s hybrid application assessment methodology leverages the real-world attack techniques of application penetration testing in combination with targeted source code review to thoroughly identify application security vulnerabilities. These full-knowledge assessments begin with automated scans of the deployed application and source code. Next, analyses of the scan results are combined with manual review to thoroughly identify potential application security vulnerabilities. In addition, the team performs a review of the application architecture and business logic to locate any design-level issues. Finally, the team performs manual exploitation and review of these issues to validate the findings. https://vinniefalco.github.io/BeastAssets/Beast%20-%20Hybrid%20Application%2... Note: The permessage-deflate vulnerability described in the report is confirmed to be fixed in the version of Beast which is included in Boost 1.66.0 Thanks