{"id":"CVE-2026-11893","summary":"Double free / use-after-free in Bouffalo Lab HCI driver send() error paths (hci_bflb)","details":"The Bluetooth HCI driver for Bouffalo Lab on-chip BLE controllers (BL60x/BL70x/BL61x), bt_bflb_send() in drivers/bluetooth/hci/hci_bflb.c, violates the bt_hci_driver_api.send() buffer-ownership contract. That contract (documented at include/zephyr/drivers/bluetooth.h) requires the buffer reference to be consumed only on success; on error the caller still owns the reference and unrefs it. The driver instead routed all error paths through a shared label that unconditionally called net_buf_unref(buf) before returning the error code, consuming the buffer on failure as well.\n\nWhen send() returns an error, the host TX path (send_buf() in subsys/bluetooth/host/conn.c) unrefs the same buffer again, believing it still owns it. This double-unref over-decrements the net_buf reference count. Because the buffer is a TX fragment whose destroy callback also decrements its still-queued parent buffer, the parent is freed prematurely while reachable on the connection TX queue, producing a use-after-free and corruption of the shared net_buf pool rather than a benign leak.\n\nThe error conditions are on the host-to-controller transmit path (controller send failure, or an unsupported H:4 packet type), so they are not driven directly by attacker-supplied radio bytes; a remote/adjacent peer can influence them only indirectly, e.g. by inducing controller TX failures under heavy link load. The consequence when reached is BLE-stack denial of service (crash / pool corruption) with possible further memory corruption, bounded to devices using one of these Bouffalo Lab on-chip controllers.","aliases":["GHSA-ph42-6rqx-728c"],"modified":"2026-08-13T08:22:29.110888Z","published":"2026-08-11T04:42:39.049Z","database_specific":{"cwe_ids":["CWE-415"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11893.json","cna_assigner":"zephyr"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11893.json"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-ph42-6rqx-728c"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-11893"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/76d92d502b30218aaf11cbbe1be180a317627bb9"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"684c9e8f32e4373a21098559f748f06915f950c9"},{"fixed":"76d92d502b30218aaf11cbbe1be180a317627bb9"}],"database_specific":{"extracted_events":[{"introduced":"4.4.0"},{"fixed":"4.4.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v4.4.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-11893.json","vanir_signatures_modified":"2026-08-13T08:22:29Z","vanir_signatures":[{"target":{"file":"drivers/bluetooth/hci/hci_bflb.c","function":"bt_bflb_send"},"deprecated":false,"digest":{"function_hash":"226881773454050183551403034836331380422","length":1265},"id":"CVE-2026-11893-15ac4de3","signature_type":"Function","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/76d92d502b30218aaf11cbbe1be180a317627bb9"},{"digest":{"line_hashes":["18072795392702696080439128071587689539","198813787744207654215890589728897653937","158820056818590277024230035500344846713","12750591706990312482651231946681551694","63213941988012335124585242776049842396","41448333500293620719504467010327834494","239981764917559746895776441528409519134","103431136381742620376045719852805650016","320592333589621037973354445665561012360","331816988530001928164642018194830563780","304743550420815742830272304802414051188","2000398518571480097176141820631283744","166285958029737031287767396829097906739","19456876009473520948894821128434440693","156004365950532716655313983041051826353","265230963830787615286421467234495083070","109999722085655267975804195666368615607","15156075185953405868213754404250594802","245636040323895663722919768696811738496","24446558233427148883025457253823405746","47758802025733740376791157932106408890","297810030243082583196032295188160182964","149661323100771570217732091394925549871","259706831093528235814162339650300558281"],"threshold":0.9},"id":"CVE-2026-11893-ad9893cb","signature_type":"Line","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/76d92d502b30218aaf11cbbe1be180a317627bb9","target":{"file":"drivers/bluetooth/hci/hci_bflb.c"},"deprecated":false}]}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H"}]}