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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-63835 being exploited?
There is no known exploitation of CVE-2026-63835 in the wild and no public exploit code.
Sources
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.