CVE-2025-23138 watch_queue: fix pipe accounting mismatch
An integer underflow in Linux kernel watch_queue accounting can cause denial of service by triggering permission errors on pipe operations.
- 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-2025-23138?
CVE-2025-23138 is a medium-severity vulnerability in Debian Debian Linux, published on 16 Apr 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:
watch_queue: fix pipe accounting mismatch
Currently, watch_queue_set_size() modifies the pipe buffers charged to user->pipe_bufs without updating the pipe->nr_accounted on the pipe itself, due to the if (!pipe_has_watch_queue()) test in pipe_resize_ring(). This means that when the pipe is ultimately freed, we decrement user->pipe_bufs by something other than what than we had charged to it, potentially leading to an underflow. This in turn can cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM.
To remedy this, explicitly account for the pipe usage in watch_queue_set_size() to match the number set via account_pipe_buffers()
(It's unclear why watch_queue_set_size() does not update nr_accounted; it may be due to intentional overprovisioning in watch_queue_set_size()?)
Which versions are affected by CVE-2025-23138?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-23138?
Apply the vendor's patch.
Is CVE-2025-23138 being exploited?
There is no known exploitation of CVE-2025-23138 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BELL-CVE-2025-23138, DEBIAN-CVE-2025-23138, GHSA-9ccw-6g9x-96r5, ROOT-OS-UBUNTU-2404-CVE-2025-23138, UBUNTU-CVE-2025-23138.