OP-TEE's subkey rollback protection can be bypassed with older subkey versions

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Summary

CVECVE-2026-44362
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-06 20:16:33 UTC
Updated2026-07-07 18:55:08 UTC
DescriptionOP-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.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.001220000 probability, percentile 0.023630000 (date 2026-07-09)

Problem Types: CWE-285 | CWE-285 CWE-285: Improper Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Trustedfirmware Op-tee All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA OP-TEE Optee Os affected >= 3.20.0, < 4.11.0 Not specified

References

ReferenceSourceLinkTags
github.com/OP-TEE/optee_os/security/advisories/GHSA-fhcg-pp56-8v75 [email protected] github.com Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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