CVE-2026-31576 media: hackrf: fix to not free memory after the device is registered in hackrf_probe()
A race condition in the Linux kernel HackRF driver allows use-after-free and double-free vulnerabilities, potentially enabling local privilege escalation or code execution.
- 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-2026-31576?
CVE-2026-31576 is a high-severity use after free vulnerability in Linux kernel, published on 24 Apr 2026. 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:
media: hackrf: fix to not free memory after the device is registered in hackrf_probe()
In hackrf driver, the following race condition occurs: ``` CPU0 CPU1 hackrf_probe() kzalloc(); // alloc hackrf_dev .... v4l2_device_register(); .... fd = sys_open("/path/to/dev"); // open hackrf fd .... v4l2_device_unregister(); .... kfree(); // free hackrf_dev .... sys_ioctl(fd, ...); v4l2_ioctl(); video_is_registered() // UAF!! .... sys_close(fd); v4l2_release() // UAF!! hackrf_video_release() kfree(); // DFB!! ```
When a V4L2 or video device is unregistered, the device node is removed so new open() calls are blocked.
However, file descriptors that are already open-and any in-flight I/O-do not terminate immediately; they remain valid until the last reference is dropped and the driver's release() is invoked.
Therefore, freeing device memory on the error path after hackrf_probe() has registered dev it will lead to a race to use-after-free vuln, since those already-open handles haven't been released yet.
And since release() free memory too, race to use-after-free and double-free vuln occur.
To prevent this, if device is registered from probe(), it should be modified to free memory only through release() rather than calling kfree() directly.
Weakness: CWE-416
Which versions are affected by CVE-2026-31576?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31576?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-31576 being exploited?
There is no known exploitation of CVE-2026-31576 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31576, DEBIAN-CVE-2026-31576, GHSA-9h3v-wrpm-q7m5, ROOT-OS-DEBIAN-11-CVE-2026-31576, ROOT-OS-DEBIAN-12-CVE-2026-31576, ROOT-OS-UBUNTU-2204-CVE-2026-31576 and 2 more.