CVE-2024-0564 is a vulnerability in the Linux kernel's Kernel Samepage Merging (KSM) feature, introduced in kernel version 4.4.0-96.119, which implements memory deduplication by merging identical memory pages across processes or virtual machines to save memory. The flaw specifically involves the 'max page sharing' parameter, which defaults to 256, limiting how many pages can be merged. An attacker co-located on the same host as a victim can exploit this by timing the unmap operation of pages to detect whether the victim's page is merged or not. The timing difference arises because if the max page sharing limit is reached, additional physical pages must be created rather than merged, causing measurable delays. This timing side channel allows the attacker to infer information about the victim's memory contents, effectively leaking data without requiring privileges or user interaction. The attack complexity is high because it requires precise timing measurements and co-residency on the same host, typically in virtualized or containerized environments. The vulnerability impacts confidentiality by leaking memory contents but does not affect integrity or availability. No patches or exploits are currently publicly available, and no known exploits in the wild have been reported. The CVSS v3.1 score is 5.3 (medium), reflecting the attack vector as adjacent network (local host), high attack complexity, no privileges required, no user interaction, and impact on confidentiality only.

For European organizations, especially those using Linux-based virtualized or cloud environments with KSM enabled, this vulnerability poses a risk of confidential data leakage between tenants or processes sharing the same physical host. This could lead to exposure of sensitive information such as cryptographic keys, passwords, or proprietary data. The impact is more pronounced in multi-tenant cloud providers, hosting providers, and enterprises running containerized workloads on shared infrastructure. Although the attack requires co-residency and high precision timing, successful exploitation could undermine data isolation guarantees critical for compliance with GDPR and other data protection regulations. The vulnerability does not affect system availability or integrity, so operational disruption is unlikely. However, the confidentiality breach potential necessitates careful risk assessment and mitigation in environments where memory deduplication is enabled and shared hosting is common.

To mitigate CVE-2024-0564, organizations should consider disabling Kernel Samepage Merging (KSM) if memory deduplication is not essential, especially in multi-tenant or cloud environments. If disabling KSM is not feasible, reducing the 'max page sharing' parameter below the default 256 can limit the side channel's effectiveness by reducing timing differences. Additionally, enforcing strict tenant isolation by avoiding co-residency of untrusted workloads on the same physical host can prevent attackers from gaining the necessary access. Monitoring and restricting access to timing sources and high-resolution timers can also raise the attack complexity. Applying kernel updates and patches as they become available from Linux distributions is critical. Organizations should audit their virtualization and container orchestration configurations to ensure that KSM is not enabled unintentionally in sensitive environments. Finally, implementing defense-in-depth controls such as encryption of sensitive data in memory and limiting privileged access reduces the risk of data leakage.