# CVE-2026-80637: netfilter: synproxy: fix unaligned memory access in timestamp adjustment

> An attacker can cause a kernel crash or performance degradation on strict alignment architectures by triggering unaligned memory access in the netfilter synproxy module.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 28 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-98132, BELL-CVE-2026-80637, DEBIAN-CVE-2026-80637, GHSA-h35g-h9xw-jfv9, UBUNTU-CVE-2026-80637

## What is CVE-2026-80637?

CVE-2026-80637 is a high-severity denial of service vulnerability in Linux, published on 28 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:

netfilter: synproxy: fix unaligned memory access in timestamp adjustment

Use get_unaligned_be32() and put_unaligned_be32() to safely read and
write the timestamp fields. This prevents performance degradation due to
unaligned memory access or even a crash on strict alignment
architectures.

This follows the implementation of timestamp parsing in the networking
stack at tcp_parse_options() and synproxy_parse_options().

## Which versions are affected by CVE-2026-80637?


## How do I fix CVE-2026-80637?

Apply the vendor's patch.

## Is CVE-2026-80637 being exploited?

There is no known exploitation of CVE-2026-80637 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80637 and fix it if it is affected.

What it is: CVE-2026-80637 is a high-severity denial of service vulnerability in Linux, published on 28 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-2026-80637 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-2026-80637/ (Markdown: https://insights.sbomify.com/CVE-2026-80637/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80637
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80637
- OSV: https://osv.dev/vulnerability/CVE-2026-80637

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80637/
Summaries are generated and may contain mistakes; the official description above is the record.