Ephemeral credentials are authentication secrets that exist only briefly, usually for one session, one API call, or one narrow task. Unlike long-lived passwords or static API keys, they expire quickly and are often tied to a specific identity, device, workload, or policy. Common examples include short-lived tokens, temporary cloud session keys, and delegated access tokens issued by an identity provider.
They matter because short lifetimes reduce the window for theft, reuse, and lateral movement. If an attacker steals an ephemeral token, it may already be invalid by the time it is abused, and it should work only for the limited scope it was issued for. Defenders use them in zero trust systems, cloud automation, and AI agent platforms to avoid standing access. In attacks, criminals often try to capture these credentials from logs, memory, browsers, or misconfigured services; in defense, teams pair them with least privilege, strong session binding, and tight audit trails.