# CVE-2023-46835: x86/AMD: mismatch in IOMMU quarantine page table levels

> A page table level mismatch in Xen's IOMMU quarantine allows devices to access uncleared memory, potentially leaking data or escalating privileges.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **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:** 5 Jan 2024
- **Updated:** 4 Nov 2025
- **Also known as:** ALPINE-CVE-2023-46835, DEBIAN-CVE-2023-46835, GHSA-c2mm-wq7p-rpm8, UBUNTU-CVE-2023-46835

## What is CVE-2023-46835?

CVE-2023-46835 is a medium-severity memory corruption vulnerability in Xen Xen, published on 5 Jan 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The current setup of the quarantine page tables assumes that the
quarantine domain (dom_io) has been initialized with an address width
of DEFAULT_DOMAIN_ADDRESS_WIDTH (48) and hence 4 page table levels.

However dom_io being a PV domain gets the AMD-Vi IOMMU page tables
levels based on the maximum (hot pluggable) RAM address, and hence on
systems with no RAM above the 512GB mark only 3 page-table levels are
configured in the IOMMU.

On systems without RAM above the 512GB boundary
amd_iommu_quarantine_init() will setup page tables for the scratch
page with 4 levels, while the IOMMU will be configured to use 3 levels
only, resulting in the last page table directory (PDE) effectively
becoming a page table entry (PTE), and hence a device in quarantine
mode gaining write access to the page destined to be a PDE.

Due to this page table level mismatch, the sink page the device gets
read/write access to is no longer cleared between device assignment,
possibly leading to data leaks.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2023-46835?

It affects 1 product.


Products: Xen Xen.

## How do I fix CVE-2023-46835?

Apply the vendor's patch.

## Is CVE-2023-46835 being exploited?

There is no known exploitation of CVE-2023-46835 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-46835 and fix it if it is affected.

What it is: CVE-2023-46835 is a medium-severity memory corruption vulnerability in Xen Xen, published on 5 Jan 2024. 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-2023-46835 in the wild and no public exploit code.

Affected product: Xen Xen. 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-2023-46835/ (Markdown: https://insights.sbomify.com/CVE-2023-46835/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-46835
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-46835
- OSV: https://osv.dev/vulnerability/CVE-2023-46835

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-46835/
Summaries are generated and may contain mistakes; the official description above is the record.