A multi-tenant system is a shared computing environment where one host, platform, or service supports multiple users, projects, or customers while keeping their data and workloads logically separated. Common examples include cloud platforms, hosted applications, shared build servers, and development environments used by more than one team.
In cyber security, multi-tenancy matters because a failure in isolation can let one tenant affect another. If permissions, containers, namespaces, or path controls are weak, an attacker may read data, alter files, or influence another tenant’s process. This is why issues like path traversal, unsafe package installation, and overbroad file permissions become more serious on shared systems: a mistake that looks local can cross a trust boundary. Defenders reduce this risk with least privilege, per-tenant access controls, filesystem sandboxing, and strict validation of file paths and install locations.