---
id: "CVE-2026-98651"
kind: "vulnerability"
aliases: ["CVE-2026-98651"]
title: "Linux kernel KVM s390: NULL pointer dereference in storage key handling"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["ibm-z", "infrastructure", "kvm", "linux-kernel", "s390"]
not_affected_if: ["kvm-not-used", "non-s390-architecture"]
published_at: "2026-10-18T16:17:18+00:00"
first_seen_at: "2026-10-23T21:57:16+00:00"
updated_at: "2026-10-25T05:19:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98651", "first_seen_at": "2026-10-23T21:57:16+00:00"}]
---

# Linux kernel KVM s390: NULL pointer dereference in storage key handling

In the Linux kernel's KVM s390 code, some callers pass a NULL oldkey pointer to dat_cond_set_storage_key(), which is then dereferenced. The sources describe a crash from this bug; they do not describe code execution or data exposure.

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

## How to check

- Check the running kernel version with `uname -r` and compare it against the fixed kernel in the NVD entry.
- Check whether KVM s390 is in use on the host (IBM Z / LinuxONE systems running KVM guests).

## Fix

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

## Timeline

- 2026-10-23T21:57:16+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98651

## From the sources

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

KVM: s390: Properly handle NULL pointer in dat_cond_set_storage_key()

Some callers pass NULL as oldkey. Calling page_cond_set_storage_key()
will cause that NULL pointer to get dereferenced.

Fix by checking for NULL and assigning the pointer to a dummy local
variable to avoid crashes.

---

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