NULL pointer dereference in Linux kernel - CVE-2026-63986

Vulnerability identifier: #VU138670

CSH Severity: Low

CVSS v4: 6.8 [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]

CVE-ID: CVE-2026-63986

CWE-ID: CWE-476

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to improper handling of an error pointer in net/ethtool/tsinfo.c when processing ethtool tsinfo dump requests. A local user can trigger the vulnerable code path to cause a denial of service.

The issue occurs because a failed prepare operation can leave no generic netlink message to cancel, leading to a kernel crash when an error pointer is passed to genlmsg_cancel().

Linux kernel
Ubuntu
linux-ibm (Ubuntu package)
linux-azure (Ubuntu package)
linux-aws (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• https://git.kernel.org/stable/c/2008f9bb1ede9b688624a241228b8e54fc74f0f6
• https://git.kernel.org/stable/c/c3fc9976f686f9a95baf87db9d387f218fd65394
• https://git.kernel.org/stable/c/d0d2c5ccd1de28368cebeef74d9c530a60eff9a5

• NULL pointer dereference in Linux kernel ethtool
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia