OP-TEE up to 4.10.x Subkey Rollback Protection core/crypto/signed_hdr.c shdr_load_pub_key Version downgrade

Summaryinfo

A vulnerability, which was classified as very critical, was found in OP-TEE up to 4.10.x. The impacted element is the function shdr_load_pub_key of the file core/crypto/signed_hdr.c of the component Subkey Rollback Protection. Executing a manipulation of the argument Version can lead to downgrade. The identification of this vulnerability is CVE-2026-44362. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in OP-TEE up to 4.10.x. It has been declared as very critical. This vulnerability affects the function shdr_load_pub_key of the file core/crypto/signed_hdr.c of the component Subkey Rollback Protection. The manipulation of the argument version with an unknown input leads to a downgrade vulnerability. The CWE definition for the vulnerability is CWE-757. A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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 3.20.0 and prior to version 4.11.0, a vulnerability in OP-TEE’s subkey rollback protection allows the use of revoked or older subkey versions because the system fails to propagate versioning data during the Trusted Application (TA) loading process. In `core/crypto/signed_hdr.c`, the function `shdr_load_pub_key()` parses subkey headers but does not assign the `subkey_version` to the runtime `shdr_pub_key` structure. As a result, the `key->version` field remains at zero regardless of the version specified in the header. When `ree_fs_ta_open()` in `core/kernel/ree_fs_ta.c` calls `check_update_version()`, it passes this zeroed version to the rollback database. Because the database never receives a non-zero version to record, it never advances, effectively bypassing the rollback check and allowing TAs signed with downgraded subkey chains to load successfully. This impacts OP-TEE mainline configurations that utilize subkey-based signing chains for Trusted Application (TA) authentication. Version 4.11.0 contains a patch. No known workarounds are available.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-44362 since 05/05/2026. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are needed for exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 07/06/2026). The MITRE ATT&CK project declares the attack technique as T1562.010.

Upgrading to version 4.11.0 eliminates this vulnerability.

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Name

• OP-TEE

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10

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