# CVE-2026-98242: dma-buf: Fix silent overflow for phys vec to sgt

> A silent integer overflow in the Linux kernel's dma-buf subsystem can cause memory corruption or denial of service when handling large MMIO sizes.

- **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:** DEBIAN-CVE-2026-98242, GHSA-vfw6-gcwv-53h6, UBUNTU-CVE-2026-98242

## What is CVE-2026-98242?

CVE-2026-98242 is a 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:

dma-buf: Fix silent overflow for phys vec to sgt

In case MMIO size is bigger than 4G and peer2peer DMA goes
through host bridge, we trigger a code path that assigns the
total linked IOVA (which is greater than 4G) to mapped_len.

Previously, `mapped_len` was declared as 32-bit `unsigned int`.
When accumulating `size_t` lengths, this leads to a silent wrap-around.
This truncation causes truncated lengths to be passed to functions
like `fill_sg_entry()`.

Fix this by changing `mapped_len` to `size_t` (64-bit). While
at it, fix similar potential overflow issues in `calc_sg_nents`
by using `check_add_overflow()` for `nents` and using
`unsigned int` for the loop iterator in `fill_sg_entry` to match.

## Which versions are affected by CVE-2026-98242?


## How do I fix CVE-2026-98242?

Apply the vendor's patch.

## Is CVE-2026-98242 being exploited?

There is no known exploitation of CVE-2026-98242 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98242 and fix it if it is affected.

What it is: CVE-2026-98242 is a 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-2026-98242 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-2026-98242/ (Markdown: https://insights.sbomify.com/CVE-2026-98242/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98242
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98242
- OSV: https://osv.dev/vulnerability/CVE-2026-98242

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98242/
Summaries are generated and may contain mistakes; the official description above is the record.