---
id: "CVE-2026-98649"
kind: "vulnerability"
aliases: ["CVE-2026-98649"]
title: "Linux kernel KVM s390: race when destroying page table entries"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "kvm", "linux-kernel", "s390x", "self-hosted"]
not_affected_if: ["no-kvm", "non-s390x-hardware"]
published_at: "2026-10-18T16:17:18+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:19:40+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98649", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel KVM s390: race when destroying page table entries

The Linux kernel's KVM s390 code could read a page table entry through a pointer several times during teardown, which allowed a race. The sources do not state what an attacker gains from the race.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the kernel version with `uname -r` and compare it against the fixed release in the kernel stable tree.
- Confirm the host runs KVM on IBM Z (s390x) hardware, for example with `lsmod | grep kvm`.

## Fix

- Update the Linux kernel to a release that includes the upstream fix for _destroy_pages_crste() (version unknown from sources).
- Reboot into the updated kernel.

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98649

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

KVM: s390: Fix race in _destroy_pages_crste()

Use READ_ONCE() in _destroy_pages_crste() to read the crste, avoid
dereferencing the pointer multiple times.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_