CVE-2026-99024 optee: register TEE devices only once fully initialized
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99024?
CVE-2026-99024 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
optee: register TEE devices only once fully initialized
optee_probe() called tee_device_register() on both the client and the supplicant device before the rest of struct optee had been initialized.
tee_device_register() calls cdev_device_add(), which does two things at once: it creates /dev/tee0 and /dev/teepriv0, and it links the device into the tee class so that class_find_device() can find it. From that moment on the device is reachable both from user space via tee_open() and from kernel space via tee_client_open_context(). The only gate in teedev_open() is tee_device_get(), which merely checks that teedev->desc is non-NULL, which was already set by tee_device_alloc(). Therefore, there is effectively no gate at all.
A context opened in that window can run against a struct optee where
- optee->call_queue.mutex is not initialized by optee_cq_init() - optee->supp mutex and completions is not initialized by optee_supp_init() - optee->rpmb_dev_mutex is not initialized yet, - the message argument cache is not initialized by optee_shm_arg_cache_init() - optee->ctx is still NULL
Any open session or invoke during this window takes uninitialized mutexes and dereferences a NULL pointer.
Fix it by moving both tee_device_register() calls down to the point where all of struct optee is set up.
[JW: adding fixes and cc]
Which versions are affected by CVE-2026-99024?
How do I fix CVE-2026-99024?
Upgrade to a fixed version.
Is CVE-2026-99024 being exploited?
There is no known exploitation of CVE-2026-99024 in the wild and no public exploit code.
Sources
Also known as AZL-110876, BELL-CVE-2026-99024, DEBIAN-CVE-2026-99024, GHSA-qp8f-jjvm-547w, UBUNTU-CVE-2026-99024.