# CVE-2026-98369: xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()

> A race condition in the Linux kernel's xfrm subsystem can cause RCU warnings and potential crashes due to missing locks and reference counts during packet reinjection.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106035, BELL-CVE-2026-98369, DEBIAN-CVE-2026-98369, GHSA-j7rh-wqhv-hc9p, UBUNTU-CVE-2026-98369

## What is CVE-2026-98369?

CVE-2026-98369 is a high-severity vulnerability in Linux, published on 6 Oct 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:

xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()

syzbot reported a suspicious RCU usage warning in ip6_pkt_drop():

  WARNING: suspicious RCU usage in ip6_pkt_drop
  include/net/addrconf.h:389 suspicious rcu_dereference_check() usage!

  Call Trace:
   __in6_dev_get_safely include/net/addrconf.h:389 [inline]
   ip6_pkt_drop+0x596/0x610 net/ipv6/route.c:4620
   ip6_pkt_discard+0x1c/0x30 net/ipv6/route.c:4651
   xfrm_trans_reinject+0x324/0x630 net/xfrm/xfrm_input.c:806
   process_one_work kernel/workqueue.c:3322 [inline]
   process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
   worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486

When commit 4f4920669d21 ("xfrm: Reinject transport-mode packets through
workqueue") converted xfrm_trans_reinject from a tasklet to a workqueue,
the reinjection loop ceased running in softirq context. Workqueue workers
run in process context where local_bh_disable() does not enter an RCU
read-side critical section under CONFIG_PREEMPT_RCU.

Because finish callbacks (such as ip6_rcv_finish) expect to run under an
RCU read lock (performing route lookups, l3mdev lookups, and accessing
RCU-protected data structures), invoking them in workqueue context without
rcu_read_lock() triggers RCU lockdep warnings.

Furthermore, packets queued to the workqueue via xfrm_trans_queue_net()
may carry non-refcounted (noref) dst entries (e.g. from ip_route_input_noref).
Additionally, on netdevice unregistration, dst_dev_put() replaces dst->dev
with blackhole_netdev, so dst entries do not keep skb->dev alive while
queued in the workqueue.

Fix these issues by:
1. Calling skb_dst_force(skb) in xfrm_trans_queue_net() while still in the
   caller's RCU section to ensure dst is reference-counted before queuing.
2. Holding a reference on skb->dev via dev_hold()/dev_put() across workqueue
   deferral so skb->dev remains valid during finish() callback processing.
3. Acquiring rcu_read_lock() around the finish callback invocation loop in
   xfrm_trans_reinject().

## Which versions are affected by CVE-2026-98369?


## How do I fix CVE-2026-98369?

Apply the vendor's patch.

## Is CVE-2026-98369 being exploited?

There is no known exploitation of CVE-2026-98369 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98369 and fix it if it is affected.

What it is: CVE-2026-98369 is a high-severity vulnerability in Linux, published on 6 Oct 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-2026-98369 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-2026-98369/ (Markdown: https://insights.sbomify.com/CVE-2026-98369/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98369
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98369
- OSV: https://osv.dev/vulnerability/CVE-2026-98369

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98369/
Summaries are generated and may contain mistakes; the official description above is the record.