{"id":"CVE-2026-11368","aliases":["EUVD-2026-52700","GHSA-85vg-gwc4-77g7"],"status":"published","title":"Use-after-free in Bluetooth host ATT TX completion on disconnect mid-transfer","description":"The Bluetooth host ATT layer (subsys/bluetooth/host/att.c) associates each in-flight ATT TX buffer with its owning channel via the static tx_meta_data_storage[] array (data-\u003eatt_chan = chan). When a buffer's last reference is dropped, its net-buf destroy callback defers the completion handling to the system workqueue (att_tx_destroy -\u003e att_tx_destroy_work_handler -\u003e att_on_sent_cb -\u003e bt_att_sent), where bt_att_sent dereferences the channel and its ATT context (sys_slist_get(\u0026att-\u003ereqs)).\n\nWhen a peer disconnects while an ATT PDU (a server notification/indication or any response) is still in flight in the controller TX path, L2CAP tears the channel down in l2cap_chan_del(): it runs the disconnected callback and then the released callback (bt_att_released), which frees the channel slab slot. Because the in-flight buffer is held by the connection TX path rather than the channel's own queue, its deferred destroy work can run after the channel has been freed. The att_on_sent_cb guard intended to drop the stale callback itself dereferences meta-\u003eatt_chan, which is now a dangling pointer into a freed (and possibly reused) slab slot.\n\nA remote peer with an ATT connection can drive this by disconnecting during routine ATT traffic; no pairing or user interaction is required to reach the ATT bearer. The result is a use-after-free read/write of freed channel memory, reliably crashing the Bluetooth host (denial of service) and, because the channel slab slot may be reused, potentially corrupting live memory.\n\nThe fix makes bt_att_released() NULL the att_chan field of every tx_meta_data_storage[] entry still referencing the channel before freeing it, so the deferred guard observes a NULL pointer and drops the callback. Teardown and the destroy work both run on the cooperative system workqueue, so the array update is serialized and needs no lock.","severity":{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00301,"percentile":0.23046,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-416"],"published":"2026-08-04T14:23:28Z","modified":"2026-10-28T11:02:17Z","products":[{"vendor":"zephyrproject","product":"zephyr"},{"vendor":"zephyrproject-rtos","product":"zephyr"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/dfdea9bad8d9b5b31c125e97fcffb549f2217caa","tags":["patch","Patch","fix"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-85vg-gwc4-77g7","tags":["Exploit","Patch","Vendor Advisory","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11368.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-11368","tags":["advisory"]},{"url":"https://github.com/zephyrproject-rtos/zephyr","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-11368","title":"Use-after-free in Bluetooth host ATT TX completion on disconnect mid-transfer","description":"The Bluetooth host ATT layer (subsys/bluetooth/host/att.c) associates each in-flight ATT TX buffer with its owning channel via the static tx_meta_data_storage[] array (data-\u003eatt_chan = chan). When a buffer's last reference is dropped, its net-buf destroy callback defers the completion handling to the system workqueue (att_tx_destroy -\u003e att_tx_destroy_work_handler -\u003e att_on_sent_cb -\u003e bt_att_sent), where bt_att_sent dereferences the channel and its ATT context (sys_slist_get(\u0026att-\u003ereqs)).\n\nWhen a peer disconnects while an ATT PDU (a server notification/indication or any response) is still in flight in the controller TX path, L2CAP tears the channel down in l2cap_chan_del(): it runs the disconnected callback and then the released callback (bt_att_released), which frees the channel slab slot. Because the in-flight buffer is held by the connection TX path rather than the channel's own queue, its deferred destroy work can run after the channel has been freed. The att_on_sent_cb guard intended to drop the stale callback itself dereferences meta-\u003eatt_chan, which is now a dangling pointer into a freed (and possibly reused) slab slot.\n\nA remote peer with an ATT connection can drive this by disconnecting during routine ATT traffic; no pairing or user interaction is required to reach the ATT bearer. The result is a use-after-free read/write of freed channel memory, reliably crashing the Bluetooth host (denial of service) and, because the channel slab slot may be reused, potentially corrupting live memory.\n\nThe fix makes bt_att_released() NULL the att_chan field of every tx_meta_data_storage[] entry still referencing the channel before freeing it, so the deferred guard observes a NULL pointer and drops the callback. Teardown and the destroy work both run on the cooperative system workqueue, so the array update is serialized and needs no lock.","status":"published","published":"2026-08-04T14:23:28.866Z","modified":"2026-08-31T23:13:07.406Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:20:04.809935Z"}],"euvd":[{"id":"EUVD-2026-52700","description":"The Bluetooth host ATT layer (subsys/bluetooth/host/att.c) associates each in-flight ATT TX buffer with its owning channel via the static tx_meta_data_storage[] array (data-\u003eatt_chan = chan). When a buffer's last reference is dropped, its net-buf destroy callback defers the completion handling to the system workqueue (att_tx_destroy -\u003e att_tx_destroy_work_handler -\u003e att_on_sent_cb -\u003e bt_att_sent), where bt_att_sent dereferences the channel and its ATT context (sys_slist_get(\u0026att-\u003ereqs)).\n\nWhen a peer disconnects while an ATT PDU (a server notification/indication or any response) is still in flight in the controller TX path, L2CAP tears the channel down in l2cap_chan_del(): it runs the disconnected callback and then the released callback (bt_att_released), which frees the channel slab slot. Because the in-flight buffer is held by the connection TX path rather than the channel's own queue, its deferred destroy work can run after the channel has been freed. The att_on_sent_cb guard intended to drop the stale callback itself dereferences meta-\u003eatt_chan, which is now a dangling pointer into a freed (and possibly reused) slab slot.\n\nA remote peer with an ATT connection can drive this by disconnecting during routine ATT traffic; no pairing or user interaction is required to reach the ATT bearer. The result is a use-after-free read/write of freed channel memory, reliably crashing the Bluetooth host (denial of service) and, because the channel slab slot may be reused, potentially corrupting live memory.\n\nThe fix makes bt_att_released() NULL the att_chan field of every tx_meta_data_storage[] entry still referencing the channel before freeing it, so the deferred guard observes a NULL pointer and drops the callback. Teardown and the destroy work both run on the cooperative system workqueue, so the array update is serialized and needs no lock.","status":"published","published":"2026-08-04T14:23:28Z","modified":"2026-08-31T23:13:07Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"high"}],"updated_at":"2026-11-02T18:01:19.818565Z"}],"nvd":[{"id":"CVE-2026-11368","description":"The Bluetooth host ATT layer (subsys/bluetooth/host/att.c) associates each in-flight ATT TX buffer with its owning channel via the static tx_meta_data_storage[] array (data-\u003eatt_chan = chan). When a buffer's last reference is dropped, its net-buf destroy callback defers the completion handling to the system workqueue (att_tx_destroy -\u003e att_tx_destroy_work_handler -\u003e att_on_sent_cb -\u003e bt_att_sent), where bt_att_sent dereferences the channel and its ATT context (sys_slist_get(\u0026att-\u003ereqs)).\n\nWhen a peer disconnects while an ATT PDU (a server notification/indication or any response) is still in flight in the controller TX path, L2CAP tears the channel down in l2cap_chan_del(): it runs the disconnected callback and then the released callback (bt_att_released), which frees the channel slab slot. Because the in-flight buffer is held by the connection TX path rather than the channel's own queue, its deferred destroy work can run after the channel has been freed. The att_on_sent_cb guard intended to drop the stale callback itself dereferences meta-\u003eatt_chan, which is now a dangling pointer into a freed (and possibly reused) slab slot.\n\nA remote peer with an ATT connection can drive this by disconnecting during routine ATT traffic; no pairing or user interaction is required to reach the ATT bearer. The result is a use-after-free read/write of freed channel memory, reliably crashing the Bluetooth host (denial of service) and, because the channel slab slot may be reused, potentially corrupting live memory.\n\nThe fix makes bt_att_released() NULL the att_chan field of every tx_meta_data_storage[] entry still referencing the channel before freeing it, so the deferred guard observes a NULL pointer and drops the callback. Teardown and the destroy work both run on the cooperative system workqueue, so the array update is serialized and needs no lock.","status":"published","published":"2026-08-04T15:16:24.843Z","modified":"2026-10-23T23:10:00.157Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"high","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:12:34.643497Z"}],"osv":[{"id":"CVE-2026-11368","title":"Use-after-free in Bluetooth host ATT TX completion on disconnect mid-transfer","description":"The Bluetooth host ATT layer (subsys/bluetooth/host/att.c) associates each in-flight ATT TX buffer with its owning channel via the static tx_meta_data_storage[] array (data-\u003eatt_chan = chan). When a buffer's last reference is dropped, its net-buf destroy callback defers the completion handling to the system workqueue (att_tx_destroy -\u003e att_tx_destroy_work_handler -\u003e att_on_sent_cb -\u003e bt_att_sent), where bt_att_sent dereferences the channel and its ATT context (sys_slist_get(\u0026att-\u003ereqs)).\n\nWhen a peer disconnects while an ATT PDU (a server notification/indication or any response) is still in flight in the controller TX path, L2CAP tears the channel down in l2cap_chan_del(): it runs the disconnected callback and then the released callback (bt_att_released), which frees the channel slab slot. Because the in-flight buffer is held by the connection TX path rather than the channel's own queue, its deferred destroy work can run after the channel has been freed. The att_on_sent_cb guard intended to drop the stale callback itself dereferences meta-\u003eatt_chan, which is now a dangling pointer into a freed (and possibly reused) slab slot.\n\nA remote peer with an ATT connection can drive this by disconnecting during routine ATT traffic; no pairing or user interaction is required to reach the ATT bearer. The result is a use-after-free read/write of freed channel memory, reliably crashing the Bluetooth host (denial of service) and, because the channel slab slot may be reused, potentially corrupting live memory.\n\nThe fix makes bt_att_released() NULL the att_chan field of every tx_meta_data_storage[] entry still referencing the channel before freeing it, so the deferred guard observes a NULL pointer and drops the callback. Teardown and the destroy work both run on the cooperative system workqueue, so the array update is serialized and needs no lock.","status":"published","published":"2026-08-04T14:23:28.866Z","modified":"2026-10-28T11:02:17.729729459Z","cvss":[{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","level":"high"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T15:44:56.310988Z"}]}}