# CVE-2026-90063: virtio-net: Ensure that TCP packets don't overflow gso_segs

> A local attacker can craft specific network packets to cause an integer overflow in the Linux kernel's virtio-net driver, potentially leading to a denial of service.

- **Severity:** Not scored
- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102951, BELL-CVE-2026-90063, DEBIAN-CVE-2026-90063, GHSA-86wj-v2pm-25hq, UBUNTU-CVE-2026-90063

## What is CVE-2026-90063?

CVE-2026-90063 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:

virtio-net: Ensure that TCP packets don't overflow gso_segs

The user can specify any gso_size in a packet crafted with an AF_PACKET
PACKET_VNET_HDR socket, even smaller than TCP_MIN_GSO_SIZE = 8. At the
same time, GSO_MAX_SIZE = 8 * GSO_MAX_SEGS = 8 * 65535. When the user
crafts a packet with gso_size < 8, there is a risk for partial GSO to
overflow the 16-bit gso_segs field when dividing the SKB length by
gso_size.

Adjust gso_size of TCP packets to be at least TCP_MIN_GSO_SIZE = 8. Keep
gso_size of UDP GSO packets, as gso_size=1 is valid and explicitly
tested at tools/testing/selftests/net/tun.c:649.

## Which versions are affected by CVE-2026-90063?


## How do I fix CVE-2026-90063?

Apply the vendor's patch.

## Is CVE-2026-90063 being exploited?

There is no known exploitation of CVE-2026-90063 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90063 and fix it if it is affected.

What it is: CVE-2026-90063 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-2026-90063 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-2026-90063/ (Markdown: https://insights.sbomify.com/CVE-2026-90063/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90063
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90063
- OSV: https://osv.dev/vulnerability/CVE-2026-90063

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90063/
Summaries are generated and may contain mistakes; the official description above is the record.