{"id":"CVE-2026-10685","title":"The Zephyr Bluetooth GATT client CCC-write response handler gatt_write_ccc_rsp() in subsys/bluetooth/host/gatt.c invoked the application's params->subscribe() callback after it had already called params->notify(conn, params, NULL, 0).\n\nP…","summary":"The Zephyr Bluetooth GATT client CCC-write response handler gatt_write_ccc_rsp() in subsys/bluetooth/host/gatt.c invoked the application's params->subscribe() callback after it had already called params->notify(conn, params, NULL, 0).\n\nP…","severity":"high","cvss":7.6,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","cwe":["CWE-416"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 2.4.0, < 4.5.0"],"patched":["zephyr 4.5.0"],"published":"2026-07-31","updated":"2026-08-07","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-10685","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/c7292f20223637232b6f962141725611a38f6a52","label":"vulnerabilities@zephyrproject.org"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-29xh-jm2m-4qvx","label":"vulnerabilities@zephyrproject.org"}],"tags":["nvd"],"epss":0.00298,"epssPercentile":0.22635,"ingestedAt":"2026-08-08T15:23:02.487Z","slug":"CVE-2026-10685","body":"## Overview\n\nThe Zephyr Bluetooth GATT client CCC-write response handler gatt_write_ccc_rsp() in subsys/bluetooth/host/gatt.c invoked the application's params->subscribe() callback after it had already called params->notify(conn, params, NULL, 0).\n\nPer the public GATT API, a notify callback with NULL data is the documented signal that the subscription has terminated and the bt_gatt_subscribe_params struct may be freed or reused by the application; calling subscribe() on the struct afterwards is a use-after-free, including an indirect call through the freed params->subscribe function pointer.\n\nThe error branch is remotely (adjacent) reachable: a Zephyr device acting as a GATT client that calls bt_gatt_subscribe() can be driven into this ordering when a connected GATT server peer answers the CCC write with an ATT Error Response (the peer-supplied error code flows through att_error_rsp -> att_handle_rsp into gatt_write_ccc_rsp).\n\nFor applications that free or recycle subscription parameters in their notification-termination handler, this results in memory corruption, a crash (denial of service), or potentially attacker-influenced control flow. The fix reorders the handler so the subscribe() callback runs before the terminating notify(NULL) in both the error and unsubscribe paths.\n\n## Affected\n\n- `zephyr >= 2.4.0, < 4.5.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `zephyr 4.5.0`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}