# CVE-2025-40058: iommu/vt-d: Disallow dirty tracking if incoherent page walk

> Improper IOMMU configuration allows non-recoverable faults when dirty tracking is enabled on incoherent page walks, causing system crashes.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **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:** 28 Oct 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-40058, DEBIAN-CVE-2025-40058, GHSA-hwfw-95mf-c924, ROOT-OS-DEBIAN-13-CVE-2025-40058, ROOT-OS-UBUNTU-2404-CVE-2025-40058, UBUNTU-CVE-2025-40058

## What is CVE-2025-40058?

CVE-2025-40058 is a high-severity vulnerability in Linux, published on 28 Oct 2025. 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: Disallow dirty tracking if incoherent page walk

Dirty page tracking relies on the IOMMU atomically updating the dirty bit
in the paging-structure entry. For this operation to succeed, the paging-
structure memory must be coherent between the IOMMU and the CPU. In
another word, if the iommu page walk is incoherent, dirty page tracking
doesn't work.

The Intel VT-d specification, Section 3.10 "Snoop Behavior" states:

"Remapping hardware encountering the need to atomically update A/EA/D bits
 in a paging-structure entry that is not snooped will result in a non-
 recoverable fault."

To prevent an IOMMU from being incorrectly configured for dirty page
tracking when it is operating in an incoherent mode, mark SSADS as
supported only when both ecap_slads and ecap_smpwc are supported.

## Which versions are affected by CVE-2025-40058?


## How do I fix CVE-2025-40058?

Apply the vendor's patch.

## Is CVE-2025-40058 being exploited?

There is no known exploitation of CVE-2025-40058 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40058 and fix it if it is affected.

What it is: CVE-2025-40058 is a high-severity vulnerability in Linux, published on 28 Oct 2025. 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-2025-40058 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-2025-40058/ (Markdown: https://insights.sbomify.com/CVE-2025-40058/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40058
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40058
- OSV: https://osv.dev/vulnerability/CVE-2025-40058

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40058/
Summaries are generated and may contain mistakes; the official description above is the record.