An isolation flaw is a weakness that allows data, code, or behavior to cross a boundary that should separate tenants, workloads, or users. In secure systems, isolation is what keeps one container, virtual machine, browser session, or account from affecting another. When that boundary fails, leftover files, shared memory, stale cache entries, misconfigured permissions, or reuse of storage can expose information that should have been erased or hidden.
In cyber security, isolation flaws matter because they can turn trusted infrastructure into a source of data leakage. Attackers may try to trigger a boundary break to read another tenant’s secrets or influence another workload. Defenders look for strict access controls, proper cleanup, zeroization, and careful reuse of disks, snapshots, and host resources. In cloud and container environments, the risk is often not a dramatic crash but quiet residual exposure: one customer’s temporary data surviving long enough to be seen by the next.