# CVE-2026-90401: md: remove REQ_NOWAIT support from raid1/10/456


- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102989, BELL-CVE-2026-90401, DEBIAN-CVE-2026-90401, GHSA-2326-xp24-ffqm, UBUNTU-CVE-2026-90401

## What is CVE-2026-90401?

CVE-2026-90401 is a high-severity vulnerability in Linux, published on 17 Sep 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

md: remove REQ_NOWAIT support from raid1/10/456

REQ_NOWAIT support in md personalities that can block internally is
fundamentally incomplete. While reads can avoid some blocking paths,
write requests can still encounter cases where one mirror succeeds while
another returns -EAGAIN. At that point md cannot distinguish queue
pressure from a real device failure, so it can neither record a bad
block nor safely retry the write without REQ_NOWAIT, leaving mirrors
with divergent data.

Rather than continue advertising REQ_NOWAIT support for personalities
that cannot implement it correctly, remove it from raid1, raid10 and
raid456. Keep REQ_NOWAIT for linear and raid0, which only remap bios to
their underlying devices; stacked limits will still clear the feature if
any component device lacks REQ_NOWAIT support.

## Which versions are affected by CVE-2026-90401?


## How do I fix CVE-2026-90401?

Upgrade to a fixed version.

## Is CVE-2026-90401 being exploited?

There is no known exploitation of CVE-2026-90401 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90401 and fix it if it is affected.

What it is: CVE-2026-90401 is a high-severity vulnerability in Linux, published on 17 Sep 2026. 
Exploitation: There is no known exploitation of CVE-2026-90401 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-2026-90401/ (Markdown: https://insights.sbomify.com/CVE-2026-90401/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90401
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90401
- OSV: https://osv.dev/vulnerability/CVE-2026-90401

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90401/
Summaries are generated and may contain mistakes; the official description above is the record.