# CVE-2026-23361: PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry

> A race condition in the Linux kernel PCI DWC endpoint driver allows host memory corruption or IOMMU errors when unmapping ATU entries during MSI-X interrupts.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:** 25 Mar 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-80573, BELL-CVE-2026-23361, DEBIAN-CVE-2026-23361, GHSA-7vjw-7j3v-c8gx, ROOT-OS-DEBIAN-11-CVE-2026-23361, ROOT-OS-DEBIAN-12-CVE-2026-23361, ROOT-OS-DEBIAN-13-CVE-2026-23361, ROOT-OS-UBUNTU-2204-CVE-2026-23361, ROOT-OS-UBUNTU-2404-CVE-2026-23361, UBUNTU-CVE-2026-23361

## What is CVE-2026-23361?

CVE-2026-23361 is a high-severity vulnerability in Linux kernel, published on 25 Mar 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:

PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry

Endpoint drivers use dw_pcie_ep_raise_msix_irq() to raise an MSI-X
interrupt to the host using a writel(), which generates a PCI posted write
transaction.  There's no completion for posted writes, so the writel() may
return before the PCI write completes.  dw_pcie_ep_raise_msix_irq() also
unmaps the outbound ATU entry used for the PCI write, so the write races
with the unmap.

If the PCI write loses the race with the ATU unmap, the write may corrupt
host memory or cause IOMMU errors, e.g., these when running fio with a
larger queue depth against nvmet-pci-epf:

  arm-smmu-v3 fc900000.iommu:      0x0000010000000010
  arm-smmu-v3 fc900000.iommu:      0x0000020000000000
  arm-smmu-v3 fc900000.iommu:      0x000000090000f040
  arm-smmu-v3 fc900000.iommu:      0x0000000000000000
  arm-smmu-v3 fc900000.iommu: event: F_TRANSLATION client: 0000:01:00.0 sid: 0x100 ssid: 0x0 iova: 0x90000f040 ipa: 0x0
  arm-smmu-v3 fc900000.iommu: unpriv data write s1 "Input address caused fault" stag: 0x0

Flush the write by performing a readl() of the same address to ensure that
the write has reached the destination before the ATU entry is unmapped.

The same problem was solved for dw_pcie_ep_raise_msi_irq() in commit
8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU mapping"), but there
it was solved by dedicating an outbound iATU only for MSI. We can't do the
same for MSI-X because each vector can have a different msg_addr and the
msg_addr may be changed while the vector is masked.

[bhelgaas: commit log]

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

## Which versions are affected by CVE-2026-23361?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23361?

Apply the vendor's patch.

## Is CVE-2026-23361 being exploited?

There is no known exploitation of CVE-2026-23361 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23361 and fix it if it is affected.

What it is: CVE-2026-23361 is a high-severity vulnerability in Linux kernel, published on 25 Mar 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-2026-23361 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-23361/ (Markdown: https://insights.sbomify.com/CVE-2026-23361/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23361
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23361
- OSV: https://osv.dev/vulnerability/CVE-2026-23361

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23361/
Summaries are generated and may contain mistakes; the official description above is the record.