Bug 2484462 (CVE-2026-40290)

Summary: CVE-2026-40290 optee_os: privilege escalation due to user-after-free race condition in shared memory teardown
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in OP-TEE (Trusted Execution Environment). A local attacker could exploit a user-after-free (UAF) race condition in the shared memory teardown logic when OP-TEE is configured as a Secure Partition Management Controller (SPMC) for Secure EL0 (S-EL0) Secure Partitions. This vulnerability occurs because the system fails to properly synchronize memory deallocation, allowing a thread to access memory after it has been freed. Successful exploitation could lead to privilege escalation, enabling the attacker to execute arbitrary code within the trusted environment.
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Bug Depends On: 2484487    
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Description OSIDB Bzimport 2026-06-03 18:02:36 UTC 
OP-TEE is a Trusted Execution Environment (TEE) designed as companion to a non-secure Linux kernel running on Arm; Cortex-A cores using the TrustZone technology. Starting in version 3.16.0 and prior to 4.11.0, a user-after-free (UAF) race condition exists in the shared memory teardown logic of FF-A  within OP-TEE SPMC/SP flows. This only applies when OP-TEE is configured as an SPMC for S-EL0 SPs, that is, with `CFG_SECURE_PARTITION=y`. The function `sp_mem_remove()`, responsible for freeing entries in `smem->receivers` and `smem->regions`, fails to acquire the global `sp_mem_lock` before performing the `free()` operations. Concurrently, other code paths, such as `sp_mem_get_receiver()`, iterate over these same lists without holding a lock, or, like `sp_mem_is_shared()`, iterate while holding the lock but are not serialized against the unprotected `free()` in `sp_mem_remove()`. This creates a cross-thread race where a thread iterating the list can acquire a pointer to an entry (e.g., `struct sp_mem_map_region` or `struct sp_mem_receiver`), and then another thread calls `sp_mem_remove()`, freeing the object. When the first thread resumes and dereferences the pointer, it results in a Use-After-Free vulnerability. Version 4.11.0 fixes the issue.