Zephyr Project up to 4.4.1 Hearing Access Service has.c security_changed null pointer dereference

Summaryinfo

A vulnerability was found in Zephyr Project Zephyr up to 4.4.1. It has been declared as critical. Affected by this issue is the function security_changed of the file subsys/bluetooth/audio/has.c of the component Hearing Access Service. Such manipulation leads to null pointer dereference. This vulnerability is documented as CVE-2026-13213. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Zephyr Project Zephyr up to 4.4.1 and classified as critical. Affected by this issue is the function security_changed of the file subsys/bluetooth/audio/has.c of the component Hearing Access Service. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

The Hearing Access Service (HAS) GATT server in subsys/bluetooth/audio/has.c installs a connection-callback set unconditionally via BT_CONN_CB_DEFINE, so security_changed() runs for every connection that establishes security even before the application has called bt_has_register(). The service attribute pointers hearing_aid_features_attr, preset_control_point_attr, and active_preset_index_attr remain NULL until bt_has_register() resolves them and sets has.registered. With CONFIG_BT_SETTINGS, settings_set_cb() restores each bonded client's persisted context at boot and unconditionally sets context->flags to BONDED_CLIENT_INIT_FLAGS (non-zero). When a previously bonded peer reconnects and re-establishes security during the startup window before bt_has_register() has been called, security_changed() sees the non-zero flags and schedules notify_work_handler, which calls bt_gatt_is_subscribed() with a still-NULL attribute pointer. That triggers an assertion (__ASSERT(attr, ...) in bt_gatt_is_subscribed()), or a NULL dereference of attr->uuid when assertions are compiled out. The result is a remotely triggerable (Bluetooth, adjacent) crash of the HAS peripheral. Exploitation requires the peer to have previously bonded with the device and to reconnect within the boot-time race window before the application registers the service; a peer that reconnects persistently can prolong the outage. Impact is denial of service only, with no memory corruption or information disclosure. The fix adds an early if (!has.registered) { return; } guard in security_changed(), so no notification work is scheduled until the GATT service is registered and its attribute pointers are valid.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-13213 since 06/24/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 4.4.2 eliminates this vulnerability. Applying the patch cb2329e090755abde8e57cf1c12aa2b9ca41a6a2 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.4.0
• 4.4.1

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