CVE-2026-23437: net: shaper: protect late read accesses to the hierarchy

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-03 · updated 2026-10-19
Weakness: CWE-662

Description

In the Linux kernel, the following vulnerability has been resolved: net: shaper: protect late read accesses to the hierarchy We look up a netdev during prep of Netlink ops (pre- callbacks) and take a ref to it. Then later in the body of the callback we take its lock or RCU which are the actual protections. This is not proper, a conversion from a ref to a locked netdev must include a liveness check (a check if the netdev hasn't been unregistered already). Fix the read cases (those under RCU). Writes needs a separate change to protect from creating the hierarchy after flush has already run.

Affected products

Linux kernel: from 6.13.1 before 6.18.20; from 6.19 before 6.19.10; 6.13, 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4, 7.0-rc5 (+2) — fixed in 6.18.20, 6.19.10

How to fix

Upgrade to a fixed version: Linux kernel 6.18.20, 6.19.10. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-23437 or the next vulnerability affects your stack