CVE-2026-40290
HIGHOP-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…
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Description
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.
Affected Products
op-teetrustedfirmwareDetection & mitigation playbook
Vendor / applianceDetect
Inventory every trustedfirmware op-tee deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2026-40290 yet — track the trustedfirmware op-tee advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-40290 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-40290. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-40290 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-40290 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.