A flaw was found in Tower's interface with SCM repositories. If a Tower project (SCM repository) definition does not have the 'delete before update' flag set, an attacker with commit access to the upstream playbook source repository could create a Trojan playbook that, when executed by Tower, modifies the checked out SCM repository to add git hooks. These git hooks could, in turn, cause arbitrary command and code execution as the user Tower runs as.