A flaw was found in the Linux kernel's memory deduplication mechanism. The max page sharing of Kernel Samepage Merging (KSM), added in Linux kernel version 4.4.0-96.119, can create a side channel. When the attacker and the victim share the same host and the default setting of KSM is "max page sharing=256", it is possible for the attacker to time the unmap to merge with the victim's page. The unmapping time depends on whether it merges with the victim's page and additional physical pages are created beyond the KSM's "max page share". Through these operations, the attacker can leak the victim's page.
Advisories
Source ID Title
EUVD EUVD EUVD-2024-16357 A flaw was found in the Linux kernel's memory deduplication mechanism. The max page sharing of Kernel Samepage Merging (KSM), added in Linux kernel version 4.4.0-96.119, can create a side channel. When the attacker and the victim share the same host and the default setting of KSM is "max page sharing=256", it is possible for the attacker to time the unmap to merge with the victim's page. The unmapping time depends on whether it merges with the victim's page and additional physical pages are created beyond the KSM's "max page share". Through these operations, the attacker can leak the victim's page.
Fixes

Solution

No solution given by the vendor.


Workaround

The mitigation shown below has a potentially significant impact on system performance and stability. It should be carefully tested prior to deployment: - Deactivation of memory deduplication Deactivating memory deduplication will effectively mitigate all attack vectors. This measure unfortunately eliminates all the highly appreciated benefits of memory deduplication, namely the increase of operational cost-effectiveness through inter-VM memory sharing. This will cause an increase in the amount of memory required and in some situations may adversely impact performance (e.g. due to slower swap space being used). It is recommended that customers test this workaround before using it in production. See https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/virtualization_tuning_and_optimization_guide/sect-ksm-deactivating_ksm for how to disable KSM from Red Hat Enterprise Linux 6 and newer. - Disabling services and firewall rules. The attack uses the response time of services on the system. By limiting access to services an attacker must connect to the service to successful carry out the exploit. Reducing the number of systems that are allowed to connect to the service will prevent an attack from working when launched outside an allowed ranges. While this does not prevent an attack from working, it will reduce the amount of systems that an attacker can launch an attack from.

History

Fri, 30 May 2025 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 25 Nov 2024 09:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-99

Wed, 16 Oct 2024 15:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-99

cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2025-10-08T16:14:29.825Z

Reserved: 2024-01-15T18:51:41.167Z

Link: CVE-2024-0564

cve-icon Vulnrichment

Updated: 2024-08-01T18:11:35.618Z

cve-icon NVD

Status : Modified

Published: 2024-01-30T15:15:08.687

Modified: 2024-11-25T09:15:05.700

Link: CVE-2024-0564

cve-icon Redhat

Severity : Low

Publid Date: 2024-01-20T00:00:00Z

Links: CVE-2024-0564 - Bugzilla

cve-icon OpenCVE Enrichment

No data.