SB2026040696 - Race condition in Linux kernel shaper

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-23437)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 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

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

The vulnerability exists due to improper locking and missing liveness check in the net: shaper hierarchy handling when processing netlink operations that read the hierarchy under RCU. A local user can send specially crafted netlink requests to cause a denial of service.

The issue occurs because a net device reference obtained during netlink operation preparation may later be accessed under RCU without verifying that the device is still live and has not already been unregistered.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0f9ea7141f365b4f27226898e62220fb98ef8dc6
• https://git.kernel.org/stable/c/348758ba74e6a348299965b16a97cfb817545cc0
• https://git.kernel.org/stable/c/581eee0890a8bde44f1fb78ad3e70502a897d583