# CVE-2026-64090: batman-adv: tt: avoid empty VLAN responses

> A flaw in the Linux kernel's batman-adv module allows empty VLAN responses, potentially causing network instability or denial of service.

- **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:** 19 Jul 2026
- **Updated:** 19 Jul 2026
- **Also known as:** BELL-CVE-2026-64090, DEBIAN-CVE-2026-64090, GHSA-j7vj-7vr5-66w9, ROOT-OS-UBUNTU-2204-CVE-2026-64090, UBUNTU-CVE-2026-64090

## What is CVE-2026-64090?

CVE-2026-64090 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 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:

batman-adv: tt: avoid empty VLAN responses

The commit 16116dac2339 ("batman-adv: prevent TT request storms by not
sending inconsistent TT TLVLs") added checks to the local (direct) TT
response code. But the response can also be done indirectly by another node
using the global TT state. To avoid such inconsistency states reported in
the original fix, also avoid sending empty VLANs for replies from the
global TT state.

## Which versions are affected by CVE-2026-64090?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64090?

Apply the vendor's patch.

## Is CVE-2026-64090 being exploited?

There is no known exploitation of CVE-2026-64090 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-2026-64090 and fix it if it is affected.

What it is: CVE-2026-64090 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 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-2026-64090 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-2026-64090/ (Markdown: https://insights.sbomify.com/CVE-2026-64090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64090
- OSV: https://osv.dev/vulnerability/CVE-2026-64090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64090/
Summaries are generated and may contain mistakes; the official description above is the record.