CVE-2025-38539 tracing: Add down_write(trace_event_sem) when adding trace event
Concurrent module loading can corrupt trace event lists, causing a kernel crash and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38539?
CVE-2025-38539 is a high-severity vulnerability in Debian Debian Linux, published on 16 Aug 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: Add down_write(trace_event_sem) when adding trace event
When a module is loaded, it adds trace events defined by the module. It may also need to modify the modules trace printk formats to replace enum names with their values.
If two modules are loaded at the same time, the adding of the event to the ftrace_events list can corrupt the walking of the list in the code that is modifying the printk format strings and crash the kernel.
The addition of the event should take the trace_event_sem for write while it adds the new event.
Also add a lockdep_assert_held() on that semaphore in __trace_add_event_dirs() as it iterates the list.
Which versions are affected by CVE-2025-38539?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38539?
Apply the vendor's patch.
Is CVE-2025-38539 being exploited?
There is no known exploitation of CVE-2025-38539 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-66371, AZL-73572, BELL-CVE-2025-38539, DEBIAN-CVE-2025-38539, GHSA-jgp9-rwc2-m645, ROOT-OS-DEBIAN-11-CVE-2025-38539 and 5 more.