CVE-2026-10774: Zephyr's Bluetooth Mesh subnet key management leaks one PSA Crypto key slot on every subnet-key teardown. In subsys/bluetooth/mesh/subnet.c, net_keys_...

Description

Zephyr's Bluetooth Mesh subnet key management leaks one PSA Crypto key slot on every subnet-key teardown. In subsys/bluetooth/mesh/subnet.c, net_keys_create() imports the Private Beacon Key into a PSA key slot under CONFIG_BT_MESH_PRIV_BEACONS (enabled by default), but subnet_keys_destroy() guarded the matching psa_destroy_key() with CONFIG_BT_MESH_V1d1. That Kconfig symbol was removed when explicit Mesh 1.0.1 support was dropped, so the destroy branch became permanently dead code and the import is never balanced by a destroy. The imbalanced teardown is reached every time subnet keys are destroyed: deleting a subnet (Config Server NetKey Delete), completing a Key Refresh Procedure (which retires the old key set), and resetting/re-provisioning the node. The over-the-air triggers are processed only under the node's device key, so they are exercisable by the provisioner or network administrator that owns the node, reachable over the Bluetooth Mesh network. With the default CONFIG_MBEDTLS_PSA_KEY_SLOT_COUNT of 16, repeated add/delete or key-refresh cycles exhaust the shared PSA key-slot pool after roughly a dozen rounds. Once exhausted, bt_mesh_private_beacon_key() and thus subnet creation fail: the node can no longer add subnets or complete key refresh, and other PSA crypto consumers on the device may be starved, until the device is rebooted. The fix aligns the destroy guard with the import guard (CONFIG_BT_MESH_PRIV_BEACONS) so each slot is freed.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.15%

4.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-401

Affected Software

Vendor	Product	Versions
Zephyrproject	Zephyr	>= 3.6.0, < 4.5.0

References

https://github.com/zephyrproject-rtos/zephyr/commit/f573da9f53630082ae95fcfd39fb021fe15f7abdPatch
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6q7g-798f-76p2Exploit, Patch, Vendor Advisory

Timeline

Published: Aug 2, 2026
Last Modified: Aug 10, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-10774?

Zephyr's Bluetooth Mesh subnet key management leaks one PSA Crypto key slot on every subnet-key teardown. In subsys/bluetooth/mesh/subnet.c, net_keys_create() imports the Private Beacon Key into a PSA key slot under CONFIG_BT_MESH_PRIV_BEACONS (enabled by default), but subnet_keys_destroy() guarded the matching psa_destroy_key() with CONFIG_BT_MESH_V1d1. That Kconfig symbol was removed when explicit Mesh 1.0.1 support was dropped, so the destroy branch became permanently dead code and the import is never balanced by a destroy. The imbalanced teardown is reached every time subnet keys are destroyed: deleting a subnet (Config Server NetKey Delete), completing a Key Refresh Procedure (which retires the old key set), and resetting/re-provisioning the node. The over-the-air triggers are processed only under the node's device key, so they are exercisable by the provisioner or network administrator that owns the node, reachable over the Bluetooth Mesh network. With the default CONFIG_MBEDTLS_PSA_KEY_SLOT_COUNT of 16, repeated add/delete or key-refresh cycles exhaust the shared PSA key-slot pool after roughly a dozen rounds. Once exhausted, bt_mesh_private_beacon_key() and thus subnet creation fail: the node can no longer add subnets or complete key refresh, and other PSA crypto consumers on the device may be starved, until the device is rebooted. The fix aligns the destroy guard with the import guard (CONFIG_BT_MESH_PRIV_BEACONS) so each slot is freed.

How severe is CVE-2026-10774?

CVE-2026-10774 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.15% probability of exploitation in the next 30 days.

How do I fix CVE-2026-10774?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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