# CVE-2026-31515: af_key: validate families in pfkey_send_migrate()

> A missing validation in the Linux kernel's af_key module allows a local attacker to trigger a kernel crash via a crafted IPsec migration request.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 22 Apr 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-83201, BELL-CVE-2026-31515, DEBIAN-CVE-2026-31515, GHSA-9285-5jpf-mwr6, ROOT-OS-DEBIAN-11-CVE-2026-31515, ROOT-OS-DEBIAN-12-CVE-2026-31515, ROOT-OS-DEBIAN-13-CVE-2026-31515, ROOT-OS-UBUNTU-2204-CVE-2026-31515, ROOT-OS-UBUNTU-2404-CVE-2026-31515, UBUNTU-CVE-2026-31515

## What is CVE-2026-31515?

CVE-2026-31515 is a medium-severity vulnerability in Linux kernel, published on 22 Apr 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:

af_key: validate families in pfkey_send_migrate()

syzbot was able to trigger a crash in skb_put() [1]

Issue is that pfkey_send_migrate() does not check old/new families,
and that set_ipsecrequest() @family argument was truncated,
thus possibly overfilling the skb.

Validate families early, do not wait set_ipsecrequest().

[1]

skbuff: skb_over_panic: text:ffffffff8a752120 len:392 put:16 head:ffff88802a4ad040 data:ffff88802a4ad040 tail:0x188 end:0x180 dev:<NULL>
 kernel BUG at net/core/skbuff.c:214 !
Call Trace:
 <TASK>
  skb_over_panic net/core/skbuff.c:219 [inline]
  skb_put+0x159/0x210 net/core/skbuff.c:2655
  skb_put_zero include/linux/skbuff.h:2788 [inline]
  set_ipsecrequest net/key/af_key.c:3532 [inline]
  pfkey_send_migrate+0x1270/0x2e50 net/key/af_key.c:3636
  km_migrate+0x155/0x260 net/xfrm/xfrm_state.c:2848
  xfrm_migrate+0x2140/0x2450 net/xfrm/xfrm_policy.c:4705
  xfrm_do_migrate+0x8ff/0xaa0 net/xfrm/xfrm_user.c:3150

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-31515?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31515?

Apply the vendor's patch.

## Is CVE-2026-31515 being exploited?

There is no known exploitation of CVE-2026-31515 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31515 and fix it if it is affected.

What it is: CVE-2026-31515 is a medium-severity vulnerability in Linux kernel, published on 22 Apr 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-2026-31515 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-31515/ (Markdown: https://insights.sbomify.com/CVE-2026-31515/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31515
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31515
- OSV: https://osv.dev/vulnerability/CVE-2026-31515

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31515/
Summaries are generated and may contain mistakes; the official description above is the record.