CVE-2026-10774
PoC largePSA key-slot resource leak in Zephyr RTOS Bluetooth Mesh subnet teardown
Zephyr's Bluetooth Mesh subnet key management leaks one PSA Crypto key slot every time subnet keys are torn down: the Private Beacon Key is imported into a PSA key slot under CONFIG_BT_MESH_PRIV_BEACONS (enabled by default), but the matching psa_destroy_key() call is guarded by the removed CONFIG_BT_MESH_V1d1 symbol, making it permanently dead code (CWE-401). The imbalance is triggered whenever subnet keys are destroyed — deleting a subnet via Config Server NetKey Delete, completing a Key Refresh Procedure that retires the old key set, or resetting/re-provisioning the node — and these management messages are processed under the node's device key, so they can be sent by the provisioner or network administrator that owns the node over the mesh network. The impact is availability rather than data exposure: with the default pool of 16 PSA key slots, roughly a dozen add/delete or key-refresh cycles exhaust the pool, after which subnet creation and key refresh fail and other PSA crypto consumers on the device may be starved until reboot. Affected users are operators of Zephyr RTOS-based Bluetooth Mesh nodes with private beacons enabled (the default) on builds without the fix; the available data does not specify affected or fixed version numbers. No in-the-wild exploitation is documented (EPSS 0.3%, not in CISA KEV), but a public advisory with PoC reference exists (GHSA-6q7g-798f-76p2).
What to do: Update affected Zephyr-based devices to a revision containing the fix that aligns the psa_destroy_key() guard with CONFIG_BT_MESH_PRIV_BEACONS (track advisory GHSA-6q7g-798f-76p2 for patched branches, as no fixed version numbers are given here). As interim mitigations, raise CONFIG_MBEDTLS_PSA_KEY_SLOT_COUNT above the default 16 to extend the time to slot exhaustion, reboot nodes that have performed many subnet add/delete or key-refresh cycles to reclaim leaked slots, and avoid unnecessary key-refresh churn. Inventory deployments built with Bluetooth Mesh and private beacons enabled (the default) to confirm exposure.
| zephyrproject zephyr | — |
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
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.
- Vendors
- zephyrproject
- Products
- zephyr
- Weakness
- CWE-401
- Vector
- CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
In the news0 stories
No ingested article mentions this CVE yet.