# CVE-2026-98470: KVM: arm64: Don't WARN on an unknown VM ioctl in protected mode

> A local attacker can crash a protected KVM host by triggering a kernel warning via an unknown ioctl, causing a panic if panic_on_warn is enabled.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98470, GHSA-j632-93gc-r86q, UBUNTU-CVE-2026-98470

## What is CVE-2026-98470?

CVE-2026-98470 is a denial of service vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

KVM: arm64: Don't WARN on an unknown VM ioctl in protected mode

kvm_pkvm_ioctl_allowed() WARNs when kvm_get_cap_for_kvm_ioctl() doesn't
find the ioctl number in vm_ioctl_caps[], and kvm_arch_vm_ioctl() calls
it for every number the generic code doesn't handle, so
ioctl(vm_fd, 0xdeadbeef) from userspace taints a pKVM host and panics it
under panic_on_warn. The lookup is fed userspace input: return false,
and userspace gets the -EINVAL kvm_arch_vm_ioctl() returns for that
number on a host without pKVM.

## Which versions are affected by CVE-2026-98470?


## How do I fix CVE-2026-98470?

Apply the vendor's patch.

## Is CVE-2026-98470 being exploited?

There is no known exploitation of CVE-2026-98470 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98470 and fix it if it is affected.

What it is: CVE-2026-98470 is a denial of service vulnerability in Linux, published on 18 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98470 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98470/ (Markdown: https://insights.sbomify.com/CVE-2026-98470/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98470
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98470
- OSV: https://osv.dev/vulnerability/CVE-2026-98470

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98470/
Summaries are generated and may contain mistakes; the official description above is the record.