# CVE-2026-98231: xfrm: serialize state GC with device state flush

> A race condition in the Linux kernel xfrm subsystem allows local attackers to trigger a use-after-free, potentially leading to privilege escalation or code execution.

- **Severity:** Not scored
- **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-106323, BELL-CVE-2026-98231, DEBIAN-CVE-2026-98231, GHSA-8c3r-c85m-88vq, UBUNTU-CVE-2026-98231

## What is CVE-2026-98231?

CVE-2026-98231 is an use after free 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: serialize state GC with device state flush

The deferred-device pass in xfrm_dev_state_flush() finds states under
xfrm_state_dev_gc_lock, but drops the lock before calling
xfrm_dev_state_free() because the driver callback may sleep.  The device
GC list does not hold an xfrm_state reference, so the state GC worker can
destroy the same state concurrently.

The race can proceed as follows:

  CPU 0                               CPU 1
  find x on the device GC list
  drop xfrm_state_dev_gc_lock
  read x->xso.dev
                                      xfrm_state_gc_destroy(x)
                                      xfrm_dev_state_free(x)
                                      xfrm_state_free(x)
  continue xfrm_dev_state_free(x)

Both paths can invoke the driver callback and drop the device reference.
CPU 0 can also access the xfrm_state after CPU 1 has freed it.

KASAN reported:

  BUG: KASAN: slab-use-after-free in xfrm_dev_state_free+0x24c/0x2a0
  Read of size 8 at addr ffff88810bbaa960 by task poc/102

  Call Trace:
   xfrm_dev_state_free+0x24c/0x2a0
   xfrm_dev_state_flush+0x353/0x400
   xfrm_dev_event+0x26d/0x3a0
   notifier_call_chain+0xc0/0x280
   __dev_notify_flags+0x169/0x250
   netif_change_flags+0xe7/0x160
   dev_change_flags+0x96/0x220
   devinet_ioctl+0x7f4/0x1880

  Allocated by task 87:
   xfrm_state_alloc+0x1e/0x5c0
   xfrm_add_sa+0xe7f/0x5820
   xfrm_user_rcv_msg+0x4f3/0x940

  Freed by task 57:
   kmem_cache_free+0xcb/0x3d0
   xfrm_state_gc_task+0x4a8/0x650
   process_one_work+0x63a/0x1070

Serialize xfrm_state destruction against the deferred-device pass with a
mutex.  Keep xfrm_state_dev_gc_lock limited to list operations and retain
the existing callback and device-reference release ordering.

## Which versions are affected by CVE-2026-98231?


## How do I fix CVE-2026-98231?

Apply the vendor's patch.

## Is CVE-2026-98231 being exploited?

There is no known exploitation of CVE-2026-98231 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98231 and fix it if it is affected.

What it is: CVE-2026-98231 is an use after free 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-2026-98231 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-2026-98231/ (Markdown: https://insights.sbomify.com/CVE-2026-98231/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98231
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98231
- OSV: https://osv.dev/vulnerability/CVE-2026-98231

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98231/
Summaries are generated and may contain mistakes; the official description above is the record.