A shared public good is a resource or protection that benefits many people at once and is difficult to restrict to one payer. In cybersecurity, this can describe controls that improve safety across an entire ecosystem, such as coordinated threat intelligence, secure standards, public alerts, or baseline protections for critical infrastructure. One organization may fund the work, but many others receive the benefit.
This matters because cyber risk often crosses company boundaries. A vulnerable supplier, cloud service, or software component can expose customers, partners, and downstream users, so security cannot always be treated as a purely private expense. Defenders use the idea of a shared public good to justify collective funding, regulation, or minimum security requirements. Attackers benefit when these shared protections are weak, because one compromise can spread through connected systems. The term helps explain why cyber resilience is increasingly viewed as a system-wide responsibility, not just an internal control.