Access mediation is the process that checks whether a user or program may use a protected resource, such as a file, device, or software function. It typically applies rules based on identity, permissions, and the requested operation. Strong mediation checks every relevant access path rather than relying on a single login prompt.
In cyber security, weak access mediation can let attackers bypass intended controls or reach data without valid authorization. For example, encrypted-storage software may show a password prompt yet fail to ensure that the password controls access to the decryption key. Defenders should verify that authentication and authorization are enforced wherever data is accessed, and that keys and privileged functions cannot be reached through alternate paths.