# CVE-2026-98881: net: bridge: remove stale rcu_barrier() in br_multicast_dev_del()


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** AZL-110614, BELL-CVE-2026-98881, DEBIAN-CVE-2026-98881, GHSA-52xp-vqwj-rp88, UBUNTU-CVE-2026-98881

## What is CVE-2026-98881?

CVE-2026-98881 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net: bridge: remove stale rcu_barrier() in br_multicast_dev_del()

This rcu_barrier() came from a time call_rcu() calls were used in
net/bridge/br_multicast.c.

Now kfree_rcu() is there, we can remove this problematic rcu_barrier()
which causes extreme RTNL pressure in many syzbot reports.

INFO: task syz-executor:77945 is blocked on a mutex likely owned by task kworker/u1024:5:36537.
task:kworker/u1024:5 state:D stack:24616 pid:36537 tgid:36537 ppid:2      task_flags:0x4208060 flags:0x00080000 last_sleep:612797637337
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
  [<ffffffff81914eaa>] context_switch+0xf2a/0x1730 kernel/sched/core.c:6483
  [<ffffffff81201143>] __schedule+0x1133/0x43a0 kernel/sched/core.c:8411
  [<ffffffff8120446b>] __schedule_loop kernel/sched/core.c:8514 [inline]
  [<ffffffff8120446b>] schedule+0xab/0x260 kernel/sched/core.c:8529
  [<ffffffff8121a093>] schedule_timeout+0xc3/0x2b0 kernel/time/sleep_timeout.c:75
  [<ffffffff81205347>] do_wait_for_common kernel/sched/completion.c:100 [inline]
  [<ffffffff81205347>] __wait_for_common kernel/sched/completion.c:121 [inline]
  [<ffffffff81205347>] wait_for_common kernel/sched/completion.c:132 [inline]
  [<ffffffff81205347>] wait_for_completion+0x2c7/0x5d0 kernel/sched/completion.c:153
  [<ffffffff81b8f27f>] rcu_barrier+0x49f/0x620 kernel/rcu/tree.c:3888
  [<ffffffff860091b3>] br_multicast_dev_del+0x303/0x350 net/bridge/br_multicast.c:4459
  [<ffffffff85fb5dbc>] br_dev_uninit+0x1c/0x40 net/bridge/br_device.c:157
  [<ffffffff8568058c>] unregister_netdevice_many_notify+0x1c1c/0x2300 net/core/dev.c:12599
  [<ffffffff8562be43>] ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
  [<ffffffff8562be43>] ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248

## Which versions are affected by CVE-2026-98881?


## How do I fix CVE-2026-98881?

Upgrade to a fixed version.

## Is CVE-2026-98881 being exploited?

There is no known exploitation of CVE-2026-98881 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98881 and fix it if it is affected.

What it is: CVE-2026-98881 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-98881 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-2026-98881/ (Markdown: https://insights.sbomify.com/CVE-2026-98881/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98881
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98881
- OSV: https://osv.dev/vulnerability/CVE-2026-98881

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98881/
Summaries are generated and may contain mistakes; the official description above is the record.