---
id: CVE-2026-13213
title: >-
  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 …
summary: >-
  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 …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
published: '2026-08-24'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T15:10:00.207'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-13213'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/cb2329e090755abde8e57cf1c12aa2b9ca41a6a2
    label: vulnerabilities@zephyrproject.org
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-9rj8-3fvm-cc9f
    label: vulnerabilities@zephyrproject.org
tags:
  - nvd
epss: 0.0017
epssPercentile: 0.05809
ingestedAt: '2026-10-12T15:55:08.128Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.