# CVE-2026-98254: swiotlb: use the adjusted address for the highmem page lookup

> A Linux kernel bug in swiotlb causes incorrect memory access during DMA operations, potentially leading to data corruption or exposure.

- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106281, BELL-CVE-2026-98254, DEBIAN-CVE-2026-98254, GHSA-hrh5-h3h2-8q3j, UBUNTU-CVE-2026-98254

## What is CVE-2026-98254?

CVE-2026-98254 is a high-severity memory corruption 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:

swiotlb: use the adjusted address for the highmem page lookup

swiotlb_bounce() reads the page frame number from the slot's recorded
orig_addr, then advances orig_addr by tlb_offset to reach the address
the caller asked about. The highmem branch mixes the two: the offset
within the page comes from the adjusted address, the page from the value
before it.

Once the adjustment crosses a page boundary the pair no longer describes
one location, and the whole copy lands one page below the intended one
for a positive tlb_offset, one above for a negative one. DMA_FROM_DEVICE
writes the device data over the wrong page and leaves the intended one
stale, DMA_TO_DEVICE feeds the device from a page the mapping may not
cover. Partial syncs through dma_sync_single_range_for_*() are what make
tlb_offset non-zero.

The branch test is picked the same way, so a slot recorded in lowmem can
be adjusted into highmem and the lowmem path then hands a highmem
address to phys_to_virt().

Take both from orig_addr once it is final and keep pfn in the branch
that uses it. PhysHighMem() asks the question straight from the address,
as dma-debug already does.

## Which versions are affected by CVE-2026-98254?


## How do I fix CVE-2026-98254?

Apply the vendor's patch.

## Is CVE-2026-98254 being exploited?

There is no known exploitation of CVE-2026-98254 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98254 and fix it if it is affected.

What it is: CVE-2026-98254 is a high-severity memory corruption 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-2026-98254 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-2026-98254/ (Markdown: https://insights.sbomify.com/CVE-2026-98254/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98254
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98254
- OSV: https://osv.dev/vulnerability/CVE-2026-98254

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98254/
Summaries are generated and may contain mistakes; the official description above is the record.