# CVE-2024-0564: Kernel: max page sharing of kernel samepage merging (ksm) may cause memory deduplication

Status: published. Published: 2024-01-30. Updated: 2026-11-06.

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.

## Remediation

- 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. (source: CNA: redhat)

## Affected products and versions

-  /  (kernel): ≥ 0; < 4.4.0-96.119 (unaffected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (kernel-rt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (kernel-rt): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (kernel): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (kernel-rt): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 5.3 (medium); CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.62% as of 2026-11-05; percentile 50.02%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-203

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/security/cve/CVE-2024-0564 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1680513 (CNA: redhat)

- https://bugzilla.redhat.com/show_bug.cgi?id=2258514 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://link.springer.com/conference/wisa (CNA: redhat)

- https://wisa.or.kr/accepted (CNA: redhat)

- https://access.redhat.com/security/cve/CVE-2024-0564 (ADP: CVE; vdb-entry, x_refsource_REDHAT, x_transferred)

- https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1680513 (ADP: CVE; x_transferred)

- https://bugzilla.redhat.com/show_bug.cgi?id=2258514 (ADP: CVE; issue-tracking, x_refsource_REDHAT, x_transferred)

- https://link.springer.com/conference/wisa (ADP: CVE; x_transferred)

- https://wisa.or.kr/accepted (ADP: CVE; x_transferred)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2024-0564; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2024-0564; retrieved 2026-11-06; source updated Not reported

Revision: 2e5b65d27bbe9a0d8d7ab7200373ee4886b49f88b215f7cac9cb3e1765ba6911

Canonical: https://y2.dev/cve/CVE-2024-0564

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