Storage remanence is leftover data that remains on reused storage media after a previous workload is gone. It can happen on disks, SSDs, virtual block devices, snapshots, and thin-provisioned storage when freed space is not fully cleared before reassignment.
In cyber security, storage remanence matters because it can break tenant isolation and expose sensitive material such as filenames, database fragments, credentials, or application state. Attackers may try to read stale bytes from shared storage, while defenders prevent exposure by zeroing blocks before reuse, securely wiping retired media, encrypting data at rest, and carefully managing snapshots and caches. In cloud and container platforms, this is a storage-layer risk: the compute boundary may stay intact, yet old data can still leak from the underlying disk layer if sanitization is incomplete.