Security vulnerabilities in software systems represent significant risks as potential entry points for malicious attacks. Traditional dashboards that display the results of static analysis security testing often use 2D or 3D visualizations, which tend to lack the spatial details required to effectively reveal issues such as the propagation of vulnerabilities across the codebase or the appearance of concurrent vulnerabilities. Additionally, most reporting solutions only treat the analysis results as an artifact that can be reviewed or edited asynchronously by developers, limiting real-time, collaborative exploration. To the best of our knowledge, no VR-based approach exists for the visualization and interactive exploration of software security vulnerabilities. Addressing these challenges, the virtual reality (VR) environment SecCityVR was developed as a proof-of-concept implementation that employs the code city metaphor within VR to visualize software security vulnerabilities as colored building floors inside the surrounding virtual city. By integrating the application's call graph, vulnerabilities are contextualized within related software components. SecCityVR supports multi-user collaboration and interactive exploration. It provides explanations and mitigations for detected issues. A user study comparing SecCityVR with the traditional dashboard find-sec-bugs showed the VR approach provided a favorable experience, with higher usability, lower temporal demand, and significantly lower frustration despite having longer task completion times. This paper and its results contribute to the fields of collaborative and secure software engineering, as well as software visualization. It provides a new application of VR code cities to visualize security vulnerabilities, as well as a novel environment for security audits using collaborative and immersive technologies.