# CVE-2026-98557: gve: DQO: fix header length used by gve_can_send_tso() for UDP GSO

> A flaw in the Linux kernel gve driver causes incorrect buffer calculations for UDP GSO packets, potentially leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98557, GHSA-jvwf-rjpr-3g5x, UBUNTU-CVE-2026-98557

## What is CVE-2026-98557?

CVE-2026-98557 is a denial of service vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

gve: DQO: fix header length used by gve_can_send_tso() for UDP GSO

gve_can_send_tso() computes how many buffers each segment of a GSO
packet would span, and for this it needs the length of the headers
that the device replicates in front of every segment.

It unconditionally uses skb_tcp_all_headers(), which reads the doff
field of the TCP header. SKB_GSO_UDP_L4 packets have no TCP header:
tcp_hdrlen() then reads one byte of the UDP payload, and header_len
can be anything in [0, 60] instead of the transport offset plus the
eight bytes of the UDP header that gve_prep_tso() programs into the
TSO context descriptor.

A wrong header length shifts all the segment boundaries computed in
the loop, so the number of buffers per segment can be over or under
estimated. In the first case, GSO is needlessly disabled for this
packet by gve_features_check_dqo() and the stack has to segment it.
In the second case, the driver hands the device a packet whose
segments span more than GVE_TX_MAX_DATA_DESCS buffers.

Use the UDP header length for SKB_GSO_UDP_L4 packets, matching what
gve_prep_tso() does.

## Which versions are affected by CVE-2026-98557?


## How do I fix CVE-2026-98557?

Apply the vendor's patch.

## Is CVE-2026-98557 being exploited?

There is no known exploitation of CVE-2026-98557 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98557 and fix it if it is affected.

What it is: CVE-2026-98557 is a denial of service vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98557 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-2026-98557/ (Markdown: https://insights.sbomify.com/CVE-2026-98557/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98557
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98557
- OSV: https://osv.dev/vulnerability/CVE-2026-98557

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98557/
Summaries are generated and may contain mistakes; the official description above is the record.