# CVE-2026-72463: xfrm: Fix dev use-after-free in xfrm async resumption

> A use-after-free vulnerability in the Linux kernel's xfrm subsystem allows attackers to cause denial of service or potentially execute code via race conditions during async resumption.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-72463, DEBIAN-CVE-2026-72463, GHSA-23r2-6gqr-3m38, UBUNTU-CVE-2026-72463

## What is CVE-2026-72463?

CVE-2026-72463 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

xfrm: Fix dev use-after-free in xfrm async resumption

xfrm async resumption hold skb->dev refcnt until after transport_finish.
However, xfrm_rcv_cb may modify skb->dev to tunnel dev without taking
device reference, such as vti_rcv_cb. The subsequent async resumption
will decrement the tunnel device's reference count, which lead to uaf
of tunnel dev and refcnt leak of orig dev as below:

unregister_netdevice: waiting for vti1 to become free. Usage count = -2

Stash the original skb->dev to fix refcnt imbalance. The new skb->dev set
by xfrm_rcv_cb can race with device teardown. Extend rcu protection over
xfrm_rcv_cb and transport_finish to prevent races.

## Which versions are affected by CVE-2026-72463?


## How do I fix CVE-2026-72463?

Apply the vendor's patch.

## Is CVE-2026-72463 being exploited?

There is no known exploitation of CVE-2026-72463 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72463 and fix it if it is affected.

What it is: CVE-2026-72463 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72463 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-2026-72463/ (Markdown: https://insights.sbomify.com/CVE-2026-72463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72463
- OSV: https://osv.dev/vulnerability/CVE-2026-72463

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72463/
Summaries are generated and may contain mistakes; the official description above is the record.