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CVE-2026-63870
ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit()
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/ieee802154. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-63870 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.176-1 | Update the kernel and reboot. Fixed in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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().
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/ieee802154/6lowpan/tx.c
- What this is
- IEEE 802.15.4 SUBSYSTEMMAINTAINERS section matched on net/ieee802154/ · linux-wpan@vger.kernel.org · Maintained
- Kernel module
- ieee802154_6lowpan
Check it on the machine
grep -wE 'CONFIG_IEEE802154|CONFIG_IEEE802154_6LOWPAN' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ieee802154_6lowpanPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_IEEE802154, CONFIG_IEEE802154_6LOWPAN
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-07-19 (3 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.13%, higher than 2.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/ieee802154
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.0 | 5.10.259 | af07fffbd53d |
| 4.0 | 5.15.210 | 3150e6d3223d |
| 4.0 | 6.1.176 | 8da95cb6ad7d |
| 4.0 | 6.6.143 | 1a827b95e62b |
| 4.0 | 6.12.94 | c1819c8defa2 |
| 4.0 | 6.18.36 | 285b0842f2e0 |
| 4.0 | 7.0.13 | 87172cc8dc49 |
| 4.0 | 7.1 | 3a5f3f7aff18 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The flaw is in the transmit path (`lowpan_xmit`) reached only when locally queued skbs are sent via `dev_queue_xmit()` (syzbot: AoE → `aoenet.c:tx` → `lowpan_xmit`), not from remote 802.15.4 packet reception.
- AC:LAttack complexity, low
- An attacker who can create a 6LoWPAN interface and queue non-IPv6 packets (or misconfigure AoE onto it) reliably triggers the uninitialized read; syzbot reproduced it deterministically with no race or rare layout dependency.
- PR:LPrivileges required, low
- Exploitation requires creating a `lowpan` RTNL link (`CAP_NET_ADMIN`, obtainable in a user namespace) and transmitting non-IPv6 frames via `AF_PACKET` or a misbound driver; no real-root-only capability is strictly required on typical userns-enabled systems.
- UI:NUser interaction, none
- No victim interaction is needed beyond the attacker (or fuzzer) configuring the interface and injecting the malformed transmit; exploitation is fully attacker-driven.
- S:UScope, unchanged
- Impact is confined to kernel memory handling and 802.15.4 transmission on the same host; it does not cross a VM, container, or IOMMU security boundary.
- C:HConfidentiality impact, high
- `lowpan_header()` copies uninitialized slab contents from skb headroom (`KMSAN: uninit-value` at `tx.c:231/240`) and uses them in 802.15.4 address fields, leaking kernel heap bytes that may be encoded into transmitted WPAN frames.
- I:HIntegrity impact, high
- Uninitialized `ieee802154_addr` values drive `wpan_dev_hard_header()` and frame transmission, allowing heap-spray-influenced 802.15.4 destinations and corrupted over-the-air frames rather than only a benign drop.
- A:HAvailability impact, high
- Successful transmission of malformed WPAN frames with attacker-influenced addressing can disrupt 802.15.4 mesh/IoT availability, and memory-safety bugs on the xmit path can escalate to kernel faults under heap-controlled conditions.