# CVE-2026-99024: optee: register TEE devices only once fully initialized

CVE-2026-99024 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-99024, released October 24, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-99024
- Priority: Routine
- CVSS: 5.3 (Moderate)
- EPSS: 0.0018
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 23, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-99024

## 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]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-99024](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99024.md) | Oct 24, 2026 |
| Linux | linux Debian 14 | 7.2.11-1 | [DEBIAN-CVE-2026-99024](https://patchblox.com/security/data/fix/linux/debian-cve-2026-99024.md) | Oct 24, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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