Bug 2502299 (CVE-2026-63870)

Summary: CVE-2026-63870 kernel: ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's 6LoWPAN (IPv6 over Low-Power Wireless Personal Area Networks) module. When a non-IPv6 packet is transmitted over a 6LoWPAN interface, the system attempts to process uninitialized data. This can lead to system instability or a denial of service, making the system unresponsive.
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Description OSIDB Bzimport 2026-07-19 15:02:40 UTC 
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().
Comment 1 Keith Grant 2026-07-21 19:27:03 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071914-CVE-2026-63870-d621@gregkh/T