# CVE-2026-64591: iommu/vt-d: Avoid WARNING in sva unbind path

> A local attacker can trigger a kernel warning and potential denial of service by unbinding an SVA device on Intel IOMMU hardware lacking PRI support.

- **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:** 6 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64591, DEBIAN-CVE-2026-64591, GHSA-xvw3-8q2r-r787, UBUNTU-CVE-2026-64591

## What is CVE-2026-64591?

CVE-2026-64591 is a denial of service vulnerability in Linux, published on 6 Aug 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:

iommu/vt-d: Avoid WARNING in sva unbind path

The Intel IOMMU driver allows SVA on devices even if they do not support
PCI/PRI. Commit 39c20c4e83b9 ("iommu/vt-d: Only handle IOPF for SVA when
PRI is supported") modified the SVA bind path to allow this configuration
by skipping IOPF enablement when PRI is missing. However, it failed to
update the unbind path.

This creates an imbalance: the unbind path attempts to disable IOPF for
a device that never had it enabled, triggering a WARNING in
intel_iommu_disable_iopf():

 WARNING: drivers/iommu/intel/iommu.c:3475 at intel_iommu_disable_iopf+0x4f/0x90d
 Call Trace:
  <TASK>
  blocking_domain_set_dev_pasid+0x50/0x70
  iommu_detach_device_pasid+0x89/0xc0
  iommu_sva_unbind_device+0x73/0x150
  xe_vm_close_and_put+0x4d2/0x1200 [xe]

Fix this by bypassing IOPF operations for SVA domains on non-PRI hardware
in both the bind and unbind paths.

## Which versions are affected by CVE-2026-64591?


## How do I fix CVE-2026-64591?

Apply the vendor's patch.

## Is CVE-2026-64591 being exploited?

There is no known exploitation of CVE-2026-64591 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64591 and fix it if it is affected.

What it is: CVE-2026-64591 is a denial of service vulnerability in Linux, published on 6 Aug 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-2026-64591 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-2026-64591/ (Markdown: https://insights.sbomify.com/CVE-2026-64591/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64591
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64591
- OSV: https://osv.dev/vulnerability/CVE-2026-64591

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64591/
Summaries are generated and may contain mistakes; the official description above is the record.