# CVE-2026-90279: md/raid5: round bitmap stripes with sector division

> Incorrect bitmap stripe alignment in Linux kernel RAID5 allows attackers to read or modify unintended disk sectors.

- **Severity:** Not scored
- **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:** AZL-102824, BELL-CVE-2026-90279, DEBIAN-CVE-2026-90279, GHSA-3w3q-m725-w3pg, UBUNTU-CVE-2026-90279

## What is CVE-2026-90279?

CVE-2026-90279 is a 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:

md/raid5: round bitmap stripes with sector division

raid5_bitmap_sector_map() aligns the array range to full RAID5 stripe
widths before converting it to component sectors. That width is
chunk_sectors multiplied by the number of data disks, and it is not
always a power of two.

Reproduce with a 4-disk RAID5, 1024-sector chunks, and three data disks.
The full-stripe width is 3072 sectors. For a one-sector write at array
sector 3072, correct rounding gives array range [3072, 6144), which maps
to component range [1024, 2048). The old round_down()/round_up() logic
instead gives [1024, 4096), which maps to [0, 1024).

Use sector_div() based arithmetic so the rounded range is aligned to the
actual RAID5 stripe width.

The deterministic mapper test now reports the fixed component range as
[1024, 2048), while the old mask-based range was [0, 1024).

## Which versions are affected by CVE-2026-90279?


## How do I fix CVE-2026-90279?

Apply the vendor's patch.

## Is CVE-2026-90279 being exploited?

There is no known exploitation of CVE-2026-90279 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90279 and fix it if it is affected.

What it is: CVE-2026-90279 is a 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-2026-90279 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-2026-90279/ (Markdown: https://insights.sbomify.com/CVE-2026-90279/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90279
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90279
- OSV: https://osv.dev/vulnerability/CVE-2026-90279

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90279/
Summaries are generated and may contain mistakes; the official description above is the record.