OP-TEE’s subkey rollback protection fails to record the subkey version when loading Trusted Applications, because the loading routine never assigns the header’s subkey_version to the runtime structure. The rollback database therefore receives a zeroed version and never updates its record, allowing Trusted Applications signed with an older or revoked subkey chain to be accepted and executed. Consequently, an attacker who can supply such a Trusted Application can run arbitrary code inside the secure world without triggering the intended security checks.

OP‑TEE OS versions from 3.20.0 up to but excluding 4.11.0 that use the default mainline configuration with subkey‑based signing chains for Trusted applications are affected. The problem exists on devices that deploy OP‑TEE as the Trusted Execution Environment for an Arm TrustZone‑enabled Cortex‑A core running a non‑secure Linux kernel.

The CVSS score of 5.5 indicates moderate severity, and the EPSS score of less than 1 % suggests a very low probability of exploitation. The vulnerability is not listed in CISA’s KEV catalog. Based on the description, it is inferred that the attacker would need to deliver a Trusted Application signed with a revoked or older subkey, which typically requires local or privileged access to the device. Bypassing the rollback check allows execution of code with the complete privileges of the secure world, potentially enabling full compromise of the device’s trusted environment.