Existential risk is a term for a severe, system-level harm scenario in which a technology could cause irreversible damage on a broad scale. In AI governance, it usually refers to worst-case outcomes such as loss of human control, cascading infrastructure failure, or other failures that threaten society-wide stability rather than a single organization.
In cyber security, the term matters because advanced AI can amplify both capability and impact. Defenders use the idea to justify stronger model evaluation, red teaming, access control, logging, and release gates for systems that can generate code, interact with tools, or operate across sensitive environments. Attackers may try to abuse the same capabilities for phishing, malware assistance, data theft, or large-scale automation. The practical lesson is to separate dramatic rhetoric from measurable risk, then reduce exposure with layered controls.