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PatchSiren cyber security CVE debrief

CVE-2026-44362 OP-TEE CVE debrief

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. This impacts OP-TEE mainline configurations that utilize subkey-based signing chains for Trusted Application (TA) authentication. The issue arises from a failure in propagating versioning data, specifically in `core/crypto/signed_hdr.c` where `shdr_load_pub_key()` does not assign `subkey_version` to the runtime `shdr_pub_key` structure, causing the `key->version` field to remain at zero. This leads to bypassing the rollback check, allowing TAs signed with downgraded subkey chains to load successfully.

Vendor
OP-TEE
Product
optee_os
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-07-07
Advisory published
2026-07-06
Advisory updated
2026-07-07

Who should care

Users of OP-TEE versions between 3.20.0 and 4.10.0 who utilize subkey-based signing chains for Trusted Application (TA) authentication should apply the patch in version 4.11.0. This involves reviewing the current OP-TEE version, identifying affected systems, and prioritizing updates based on operational impact and security posture.

Technical summary

In OP-TEE, 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. The issue arises because the system fails to propagate versioning data during the Trusted Application (TA) loading process. Specifically, 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.

Defensive priority

Apply the patch in OP-TEE version 4.11.0 to fix the subkey rollback protection bypass vulnerability.

Recommended defensive actions

  • Apply the patch in OP-TEE version 4.11.0
  • Inventory and update OP-TEE to version 4.11.0 if using a vulnerable version
  • Monitor for Trusted Application (TA) loading process anomalies
  • Implement compensating controls for subkey-based signing chains
  • Exception tracking for TA authentication failures

Evidence notes

The CVE record was published on 2026-07-06T20:16:33.950Z and has not been modified since then. The NVD entry is currently Analyzed. Evidence is limited to CVE and NVD entries; further verification is needed to assess affected deployments and validate vendor guidance.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-06T20:16:33.950Z and has not been modified since then.