CVE-2026-63991 Bluetooth: 6lowpan: check skb_clone() return value in send_mcast_pkt()

What is CVE-2026-63991?

CVE-2026-63991 is a medium-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:

Bluetooth: 6lowpan: check skb_clone() return value in send_mcast_pkt()

The skb_clone() function can return NULL if memory allocation fails. send_mcast_pkt() calls skb_clone() without checking the return value, which can lead to a NULL pointer dereference in send_pkt() when it dereferences skb->data. Add a NULL check after skb_clone() and skip the peer if the clone fails.

Weakness: CWE-476

Which versions are affected by CVE-2026-63991?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-63991?

Apply the vendor's patch.

Is CVE-2026-63991 being exploited?

There is no known exploitation of CVE-2026-63991 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-63991, DEBIAN-CVE-2026-63991, GHSA-5hvm-w645-g9wh, ROOT-OS-UBUNTU-2204-CVE-2026-63991, UBUNTU-CVE-2026-63991.