NULL pointer dereference in Linux kernel - CVE-2026-63991
Published: July 20, 2026
Vulnerability identifier: #VU138659
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63991
CWE-ID: CWE-476
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a null pointer dereference in send_mcast_pkt() in the Bluetooth 6LoWPAN subsystem when processing multicast packets. A local user can trigger a memory allocation failure that leads to dereferencing a NULL skb pointer in send_pkt() to cause a denial of service.
How to mitigate CVE-2026-63991
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/2061d080a013c0ec0a56162cd501fb36d2befc26
- https://git.kernel.org/stable/c/3c40d381ce04f9575a5d8b542898183c3b4b38dc
- https://git.kernel.org/stable/c/3d5d81d294ba09487c86bc4ba33dc4a4bec5d215
- https://git.kernel.org/stable/c/9903a04becf059e44cccf625e23689b7d4378384
- https://git.kernel.org/stable/c/9afcb5ea080af13aab37930da627db43bd277665
- https://git.kernel.org/stable/c/b06203ac5f12929d79146bb9f063c2af1d679e63
- https://git.kernel.org/stable/c/d630c4b25f36e0e68461561e4c70957ec37fdedd
- https://git.kernel.org/stable/c/e673889a35a5e4c586d0fae67d8755ca4367d3e2