Medium · CVSS 5.3CVE-2024-0564

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

Answer in brief

CVE-2024-0564 records a Medium severity (CVSS 5.3) vulnerability in Kernel: max page sharing of kernel samepage merging (ksm) may cause memory deduplication. The current sources do not mark it as known exploited. The current feed maps Red Hat/kernel (generic), Red Hat/kernel-rt (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jan 30, 2024Updated Nov 6, 2026Source checked Nov 6, 2026First seen by HOL Nov 6, 2026Material review Nov 6, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/kernel (generic), Red Hat/kernel-rt (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/kernelgeneric	*	Not reported
Red Hat/kernel-rtgeneric	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/kernel, Red Hat/kernel-rt.
Review the reported fix. Source-reported 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.

Evidence timeline and material changes

Published upstream
Jan 30, 2024
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Nov 6, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.

Package

Affected range

Fixed version

Red Hat/kernelgeneric

Not reported

Red Hat/kernel-rtgeneric

Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/kernel, Red Hat/kernel-rt.

Review the reported fix. Source-reported 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.

Sources and claim methodology

Upstream source description

Quoted source text, attributed separately from HOL analysis.