# CVE-2026-72407: geneve: validate inner network offset in geneve_gro_complete()

> A race condition in the Linux kernel's Geneve GRO implementation allows out-of-bounds memory access, potentially leading to code execution or system crashes.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-72407, GHSA-gp9v-9c23-fw32, UBUNTU-CVE-2026-72407

## What is CVE-2026-72407?

CVE-2026-72407 is a critical memory corruption vulnerability in Linux, published on 15 Aug 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:

geneve: validate inner network offset in geneve_gro_complete()

Even with both paths gated on gs->gro_hint, geneve_gro_complete()
re-derives the inner dispatch type and length from the packet and the
current gs->gro_hint, independently of geneve_gro_receive(). The two can
disagree if gs->gro_hint flips under a concurrent geneve_quiesce()/
geneve_unquiesce() (sk_user_data is NULL across a synchronize_net()), or if
the re-read option bytes differ from the ones receive parsed.

geneve_gro_receive() already records the inner network header position in
NAPI_GRO_CB()->inner_network_offset. Have geneve_gro_complete() compute the
offset it is about to dispatch at, adding ETH_HLEN in the ETH_P_TEB case
where eth_gro_complete() steps over the inner MAC header, and bail out if
it lands past inner_network_offset.

Use a lower bound rather than exact equality: between gh_len and the inner
L3 header, geneve_gro_receive() may also have pulled an inner VLAN tag
(vlan_gro_receive() advances the recorded offset past it), which only moves
inner_network_offset further out. A valid frame therefore always satisfies
inner_nh <= inner_network_offset, while a gh_len inflated by a hint
gro_receive() did not honour dispatches past the validated inner header,
i.e. the out-of-bounds completion. Only the latter is rejected.

## Which versions are affected by CVE-2026-72407?


## How do I fix CVE-2026-72407?

Apply the vendor's patch.

## Is CVE-2026-72407 being exploited?

There is no known exploitation of CVE-2026-72407 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72407 and fix it if it is affected.

What it is: CVE-2026-72407 is a critical memory corruption vulnerability in Linux, published on 15 Aug 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-2026-72407 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-2026-72407/ (Markdown: https://insights.sbomify.com/CVE-2026-72407/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72407
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72407
- OSV: https://osv.dev/vulnerability/CVE-2026-72407

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72407/
Summaries are generated and may contain mistakes; the official description above is the record.