CVE-2026-45702: OP-TEE Type Confusion Vulnerability in FFA_MEM_SHARE Processing

Technical summary

CVE-2026-45702 is a type confusion vulnerability in OP-TEE OS that emerges during processing of FFA_MEM_SHARE requests originating from the rich operating system. The flaw is specific to deployments where OP-TEE operates as a Secure Partition Manager Controller (SPMC) for S-EL0 secure partitions, requiring both CFG_CORE_SEL1_SPMC and CFG_SECURE_PARTITION configuration flags to be enabled. The type confusion occurs when the TEE misinterprets or mishandles the memory region attributes or type information embedded in the FFA call, leading to improper memory state management. While the vulnerability does not permit information disclosure or privilege escalation across security boundaries, it can be weaponized to cause service disruption through resource exhaustion or incorrect state transitions within the secure domain. Affected versions span from 4.3.0 through 4.10.x; version 4.11.0 introduces corrected type handling logic.

Business impact

Organizations deploying OP-TEE as a foundational security component in Arm-based systems—particularly in IoT, embedded devices, automotive platforms, or edge computing environments—face availability risk. A high-privileged attacker can induce denial of service, causing the trusted execution environment to become unresponsive or enter an invalid state, which may cascade into broader system instability or require manual intervention and reboots. This is especially concerning in production environments where TEE availability underpins security-critical functions such as cryptographic key management, secure boot validation, or attestation services. The risk is moderate because exploitation requires high privilege level and the impact is availability-focused rather than confidentiality or integrity-focused.

Affected systems

OP-TEE versions 4.3.0 through 4.10.x are vulnerable when configured with both CFG_CORE_SEL1_SPMC=y (enabling SPMC mode) and CFG_SECURE_PARTITION=y (enabling secure partitions). Systems using OP-TEE in simpler configurations—such as single-TEE deployments without secure partition support—are not affected. The vulnerability is specific to Arm Cortex-A processors using TrustZone technology. Vulnerability is not present in OP-TEE 4.11.0 and later versions. Verify your build configuration and version against the TrustedFirmware OP-TEE release notes to determine exposure.

Exploitability

Exploitation requires an attacker to possess high privilege level on the normal world operating system (e.g., root or kernel-level access). This significantly constrains the threat; the attacker must already have gained substantial system access before they can abuse this flaw. The attack itself is straightforward—crafting a malformed FFA_MEM_SHARE request—but triggering it in a production environment requires prior compromise. The vulnerability is not known to be exploited in the wild and has not been added to the CISA Known Exploited Vulnerabilities (KEV) catalog. Remote exploitation is not feasible; the attack surface is limited to local authenticated users or privileged processes.

Remediation

Organizations should update OP-TEE to version 4.11.0 or a later release. Prior to updating, audit your current OP-TEE deployment to confirm the presence of both CFG_CORE_SEL1_SPMC=y and CFG_SECURE_PARTITION=y build flags; if neither flag is set, your system is not vulnerable. For systems unable to update immediately, restrict system access to trusted administrative users and monitor for anomalous TEE behavior. Test the update in a non-production environment first, as TEE updates may require secure boot or firmware re-provisioning procedures specific to your platform.

Patch guidance

Patch availability: OP-TEE 4.11.0 and later contain the fix. To apply: (1) obtain the latest OP-TEE source or binary release from the TrustedFirmware project; (2) verify that both CFG_CORE_SEL1_SPMC and CFG_SECURE_PARTITION flags are present in your build configuration to confirm you were vulnerable; (3) rebuild OP-TEE or update the TEE binary in your firmware image according to your platform's secure boot and firmware update procedures; (4) re-provision secure boot keys if required by your device; (5) validate TEE functionality post-update (e.g., verify attestation, key provisioning, and secure partition startup). Consult your platform vendor's integration guide and TrustedFirmware release notes for build and deployment specifics.

Detection guidance

Identify vulnerable instances by: (1) Checking OP-TEE version via tee-supplicant logs, OP-TEE initialization output, or firmware version commands; (2) Confirming build configuration by examining OP-TEE source tree or consulting your platform firmware documentation for CFG_CORE_SEL1_SPMC and CFG_SECURE_PARTITION flags; (3) Monitoring TEE logs and system logs for unexpected TEE failures, state corruption messages, or restart cycles correlating with memory-sharing operations; (4) Testing: in a controlled lab environment, analyze FFA call handling with instrumented OP-TEE or TEE-aware debuggers to confirm the type confusion is present before patching. Runtime detection of active exploitation is challenging because the impact manifests as a crash or state error rather than a suspicious network connection or file activity.

Why prioritize this

This vulnerability should be prioritized based on your deployment model. If your infrastructure includes Arm-based devices running OP-TEE in SPMC + secure partition mode (common in advanced IoT, automotive, or confidential computing platforms), schedule patching within your regular security update cycle—aim for 60–90 days. If you run simpler OP-TEE configurations without SPMC and secure partitions, deprioritize this flaw and focus on other exposure. The CVSS 4.4 (Medium) score reflects limited exploitability (high privilege required) and availability-only impact; however, the criticality of TEE availability in security-sensitive systems means business context should override raw score when making patch decisions.

Risk score, explained

The CVSS 3.1 score of 4.4 (MEDIUM) reflects: Attack Vector = Local (AV:L) because exploitation requires prior access to the system; Privilege Required = High (PR:H) because only high-privileged processes can craft FFA_MEM_SHARE requests; User Interaction = None (UI:N) because no user action is needed; Scope = Unchanged (S:U) meaning the impact does not cross security boundaries; Confidentiality = None (C:N) because data exposure does not occur; Integrity = None (I:N) because data corruption is not a direct outcome; Availability = High (A:H) because the TEE can become unresponsive. The moderate score accurately reflects that while availability impact is significant, the high barrier to exploitation (requiring high privilege) limits the overall risk in well-segmented systems.

Frequently asked questions