# CVE-2026-64207: net/sched: dualpi2: fix GSO backlog accounting

> A NULL pointer dereference in the Linux kernel's DualPI2 scheduler can cause a system crash when processing GSO packets with QFQ as the parent.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 20 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64207, DEBIAN-CVE-2026-64207, GHSA-mghj-w558-vm84, UBUNTU-CVE-2026-64207

## What is CVE-2026-64207?

CVE-2026-64207 is a medium-severity vulnerability in Linux kernel, published on 20 Jul 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:

net/sched: dualpi2: fix GSO backlog accounting

When DualPI2 splits a GSO skb into N segments, it propagates N
additional packets to its parent before returning NET_XMIT_SUCCESS.
The parent then accounts for the original skb once more, leaving its
qlen one larger than the number of packets actually queued.

With QFQ as the parent, after all real packets are dequeued, QFQ still
has a non-zero qlen while its in-service aggregate has no active
classes. qfq_choose_next_agg() returns NULL and qfq_dequeue() passes
the result to qfq_peek_skb(), causing a NULL pointer dereference.

Follow the same pattern used by tbf_segment() and taprio: count only
successfully queued segments, propagate the difference between the
original skb and those segments, and return NET_XMIT_SUCCESS whenever
at least one segment was queued.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-64207?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64207?

Apply the vendor's patch.

## Is CVE-2026-64207 being exploited?

There is no known exploitation of CVE-2026-64207 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64207 and fix it if it is affected.

What it is: CVE-2026-64207 is a medium-severity vulnerability in Linux kernel, published on 20 Jul 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-2026-64207 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-64207/ (Markdown: https://insights.sbomify.com/CVE-2026-64207/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64207
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64207
- OSV: https://osv.dev/vulnerability/CVE-2026-64207

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64207/
Summaries are generated and may contain mistakes; the official description above is the record.