# CVE-2026-97522: mptcp: fix bad accounting in __mptcp_subflow_push_pending()

> A bug in Linux kernel MPTCP accounting can cause byte counter mismatches, potentially leading to denial of service conditions.

- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104567, BELL-CVE-2026-97522, DEBIAN-CVE-2026-97522, GHSA-pwwm-ccjp-fwfv, UBUNTU-CVE-2026-97522

## What is CVE-2026-97522?

CVE-2026-97522 is a denial of service vulnerability in Linux, published on 25 Sep 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:

mptcp: fix bad accounting in __mptcp_subflow_push_pending()

If __subflow_push_pending() errors out we should avoid updating the
copied byte counters, to avoid mismatch push call later on.

## Which versions are affected by CVE-2026-97522?


## How do I fix CVE-2026-97522?

Apply the vendor's patch.

## Is CVE-2026-97522 being exploited?

There is no known exploitation of CVE-2026-97522 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97522 and fix it if it is affected.

What it is: CVE-2026-97522 is a denial of service vulnerability in Linux, published on 25 Sep 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-2026-97522 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-2026-97522/ (Markdown: https://insights.sbomify.com/CVE-2026-97522/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97522
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97522
- OSV: https://osv.dev/vulnerability/CVE-2026-97522

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97522/
Summaries are generated and may contain mistakes; the official description above is the record.