Integrating security activities into the software development lifecycle to detect security flaws is essential for any project. These activities produce reports that must be looped back to project stakeholders like developers to enable security improvements. This so-called Feedback Loop is a crucial part of any project and is required by various security standards and models. However, the operation of this loop presents various challenges. Starting with the need to ensure that feedback data is of sufficient quality to the need of providing different stakeholders with the targeted information they require. Minding these challenges during the operation is essential to avoid risks like the security improvements being implemented with a delay or crucial security vulnerabilities not being mitigated at all. In this work, we propose a novel approach for treating reports from security activities as knowledge in a Knowledge Base (KB). We analyze typical challenges when employing the Feedback Loop and identify constraints for procedures addressing those in industrial development projects. Using these constraints, we develop a semantic KB framework for managing security reports. Based on this framework, we instantiate a KB and implement it for one exemplary use case, covering existing challenges for the security Feedback Loop. Finally, we deploy the KB in a DevOps-oriented setup with data from automated security testing. In this setup, we compare the manual management of security reports with our KB and discuss the results. We conclude that using our semantic KB framework supports and improves the Feedback Loop for security reports by addressing typical challenges like duplicates when utilized in software development projects.