What is the potential risk when processing on a virtualized instance can be detected by other instances on the same host?

The correct answer is information bleed. This term refers to the potential risk that sensitive information can be inadvertently exposed from one virtualized instance to another on the same physical host. When multiple virtual machines (VMs) run on a shared physical resource, there is a risk that vulnerabilities or misconfigurations may allow one VM to access data being processed by another. This can happen due to improper isolation between virtual instances, leading to the unintended sharing of sensitive information.

Information bleed is particularly concerning in cloud environments where multiple tenants may share the same underlying infrastructure. Protecting against this risk involves implementing strict access controls, ensuring proper virtualization security measures, and employing techniques like hypervisor security to prevent one instance from gleaning information from another.

Data leakage, while related, generally refers to a broader context of unauthorized data transfer across network boundaries, not specifically within a virtualized environment. Session hijacking involves taking over a user's active session, and phishing attacks focus on tricking individuals into revealing personal information, neither of which directly pertains to the risks associated with virtualization.