# CVE-2026-63870: ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit()

> A Linux kernel vulnerability allows denial of service via uninitialized memory access when non-IPv6 packets are sent over 6LoWPAN interfaces.

- **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:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-63870, DEBIAN-CVE-2026-63870, GHSA-phq6-q8j5-j858, ROOT-OS-UBUNTU-2204-CVE-2026-63870, UBUNTU-CVE-2026-63870

## What is CVE-2026-63870?

CVE-2026-63870 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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:

ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit()

The aoe driver (or similar) generates a non-IPv6 packet
(e.g., ETH_P_AOE) and queues it for transmission via dev_queue_xmit()
on a 6LoWPAN interface (configured by the user or test case).

Since the packet is not IPv6, the 6LoWPAN header_ops->create function
(lowpan_header_create or header_create) returns early without initializing
the lowpan_addr_info structure in the skb headroom.

In the transmit function (lowpan_xmit), the driver calls lowpan_header
(or setup_header) which unconditionally copies and uses the lowpan_addr_info
from the headroom, which contains uninitialized data.

Fix this by dropping non IPv6 packets.

A similar fix is needed in net/bluetooth/6lowpan.c bt_xmit().

Weakness: CWE-908 (Use of Uninitialized Resource), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-63870?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-63870?

Apply the vendor's patch.

## Is CVE-2026-63870 being exploited?

There is no known exploitation of CVE-2026-63870 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-2026-63870 and fix it if it is affected.

What it is: CVE-2026-63870 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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-2026-63870 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-2026-63870/ (Markdown: https://insights.sbomify.com/CVE-2026-63870/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63870
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63870
- OSV: https://osv.dev/vulnerability/CVE-2026-63870

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63870/
Summaries are generated and may contain mistakes; the official description above is the record.