Energy security is one of the most important topics in energy-related literature. As such, various concepts and dimensions are introduced to contribute to energy security assessments. However, the literature lacks an approach to prioritise these dimensions, as they cannot always be addressed simultaneously. This study is the first step in investigating the importance and prioritisation of energy security dimensions by focusing on the context of community energy systems. Such collective and decentralised energy systems are gaining momentum in the energy transition context; however, they have received minimal attention on their energy security aspects. First, a literature review is conducted to gain an overview of the studied energy security dimensions, highlighting dimensions such as energy availability and infrastructure that are studied the most. In contrast, environment and societal effect dimensions have received minimal attention. Next, an existing agent-based model is used to assess the importance of energy security dimensions and their priority in community energy systems. The results revealed that infrastructure and governance are the most impactful dimensions for the energy security assessment of community energy systems. Energy prices were one of the least influential dimensions in energy security assessments. The study also explored various existing energy security concepts and proposed the most suitable one in the energy communities' context. A research agenda emphasising the need to study governance, societal effects and environmental dimensions is also presented. Lastly, infrastructure, governance, environment and societal effects are concluded to be the most crucial energy security dimensions for community energy systems.