# CVE-2026-90332: PCI: dwc: ep: Flush cached MSI write before unmapping the iATU

> A race condition in the Linux kernel PCI DWC endpoint driver may drop or misroute MSI writes during address changes, potentially causing data corruption or denial of service.

- **Severity:** High 8.2 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-90332, GHSA-4589-rc6p-3w23, UBUNTU-CVE-2026-90332

## What is CVE-2026-90332?

CVE-2026-90332 is a high-severity vulnerability in Linux, published on 17 Sep 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 cached MSI write before unmapping the iATU

The MSI-X path already flushes any posted MSI-X write before tearing down
its iATU mapping. That was added by commit c22533c66cca ("PCI: dwc: ep:
Flush MSI-X write before unmapping its ATU entry") to make sure the write
reaches the Root Complex before the outbound window that translates it
disappears.

The MSI path has the same problem but no equivalent flush. When the
Endpoint driver caches an MSI target address and later observes that the
Root Complex has changed it, dw_pcie_ep_raise_msi_irq() unmaps the existing
iATU entry and reprograms it for the new address. Between the last MSI
writel() and the unmap there may still be a posted write sitting in the
fabric, and unmapping the iATU entry can drop or misroute that write.

Fix this by reading back from the mapped MSI window before the unmap. The
readback drains any posted MSI writes through the same iATU entry that
mapped them, which is the same logic the MSI-X path uses.

[mani: commit log]

## Which versions are affected by CVE-2026-90332?


## How do I fix CVE-2026-90332?

Apply the vendor's patch.

## Is CVE-2026-90332 being exploited?

There is no known exploitation of CVE-2026-90332 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90332 and fix it if it is affected.

What it is: CVE-2026-90332 is a high-severity vulnerability in Linux, published on 17 Sep 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-2026-90332 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-2026-90332/ (Markdown: https://insights.sbomify.com/CVE-2026-90332/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90332
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90332
- OSV: https://osv.dev/vulnerability/CVE-2026-90332

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90332/
Summaries are generated and may contain mistakes; the official description above is the record.