# CVE-2026-63835: batman-adv: v: prevent OGM aggregation on disabled hardif

> A race condition in the Linux kernel batman-adv module allows memory leaks via disabled interfaces, potentially leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-63835, DEBIAN-CVE-2026-63835, GHSA-vcwj-xjx6-gq5q, ROOT-OS-DEBIAN-11-CVE-2026-63835, ROOT-OS-UBUNTU-2204-CVE-2026-63835, UBUNTU-CVE-2026-63835

## What is CVE-2026-63835?

CVE-2026-63835 is a memory corruption vulnerability in Linux, 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: v: prevent OGM aggregation on disabled hardif

When an interface gets disabled, the worker is correctly disabled by
batadv_hardif_disable_interface() -> ... -> batadv_v_ogm_iface_disable().
In this process, the skb aggr_list is also freed.

But batadv_v_ogm_send_meshif() can still queue new skbs (via
batadv_v_ogm_queue_on_if()) to the aggr_list. This will only stop after all
cores can no longer find the RCU protected list of hard interfaces. These
queued skbs will never be freed or consumed by batadv_v_ogm_aggr_work.

The batadv_v_ogm_iface_disable() function must block
batadv_v_ogm_queue_on_if() to avoid leak of skbs.

## Which versions are affected by CVE-2026-63835?


## How do I fix CVE-2026-63835?

Apply the vendor's patch.

## Is CVE-2026-63835 being exploited?

There is no known exploitation of CVE-2026-63835 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63835 and fix it if it is affected.

What it is: CVE-2026-63835 is a memory corruption vulnerability in Linux, 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-2026-63835 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-2026-63835/ (Markdown: https://insights.sbomify.com/CVE-2026-63835/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63835
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63835
- OSV: https://osv.dev/vulnerability/CVE-2026-63835

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63835/
Summaries are generated and may contain mistakes; the official description above is the record.