CVE-2025-40021 tracing: dynevent: Add a missing lockdown check on dynevent
Attackers with high privileges can bypass kernel lockdown restrictions via the dynamic events interface in the Linux kernel.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40021?
CVE-2025-40021 is a vulnerability in Linux, published on 24 Oct 2025. 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:
tracing: dynevent: Add a missing lockdown check on dynevent
Since dynamic_events interface on tracefs is compatible with kprobe_events and uprobe_events, it should also check the lockdown status and reject if it is set.
Which versions are affected by CVE-2025-40021?
How do I fix CVE-2025-40021?
Apply the vendor's patch.
Is CVE-2025-40021 being exploited?
There is no known exploitation of CVE-2025-40021 in the wild and no public exploit code.
Sources
Also known as AZL-68811, BELL-CVE-2025-40021, DEBIAN-CVE-2025-40021, GHSA-hmw5-3qc9-5j9m, ROOT-OS-DEBIAN-11-CVE-2025-40021, ROOT-OS-UBUNTU-2404-CVE-2025-40021 and 1 more.