# CVE-2026-98262: ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY

> A kernel bug causes system boot failure on specific hardware when 32-bit DMA is forced, requiring a patch to clear specific AHCI registers.

- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106389, BELL-CVE-2026-98262, DEBIAN-CVE-2026-98262, GHSA-599j-5783-gx62, UBUNTU-CVE-2026-98262

## What is CVE-2026-98262?

CVE-2026-98262 is a denial of service vulnerability in Linux, published on 6 Oct 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:

ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY

A user reported that commit 105c42566a55 ("ata: ahci: force 32-bit DMA for
JMicron JMB582/JMB585") made the JMicron JMB585 unusable on his board.

The failure is seen as soon as the ahci driver is probed, and booting with
iommu=off does not solve the problem.

Looking at the AHCI specification, PxCLBU and PxFBU are both read only '0'
for HBAs that do not support 64-bit addressing.

For HBAs that do support 64-bit addressing, the registers are read write,
with a reset value that is Implementation Specific.

When using the AHCI_HFLAG_32BIT_ONLY flag, the HBA does support 64-bit
addressing, and a 32-bit DMA mask is set by simply clearing HOST_CAP_64.
Thus, in this case, we need to explicitly clear the registers to 0.

## Which versions are affected by CVE-2026-98262?


## How do I fix CVE-2026-98262?

Apply the vendor's patch.

## Is CVE-2026-98262 being exploited?

There is no known exploitation of CVE-2026-98262 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98262 and fix it if it is affected.

What it is: CVE-2026-98262 is a denial of service vulnerability in Linux, published on 6 Oct 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-2026-98262 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-2026-98262/ (Markdown: https://insights.sbomify.com/CVE-2026-98262/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98262
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98262
- OSV: https://osv.dev/vulnerability/CVE-2026-98262

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98262/
Summaries are generated and may contain mistakes; the official description above is the record.