{"id":"CVE-2026-79982","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-79982","generatedAt":"2026-10-28T02:21:09.467Z","title":"With the HCI buffer sizes recommended for full-featured controllers, an unauthenticated attacker within Bluetooth range can supply the overflowing bytes: a connected peer that negotiates Data Length Extension can send ACL fragments up to…","description":"The Bluetooth HCI USB transport class of the new USB device stack, subsys/usb/device_next/class/bt_hci.c, copies every controller-to-host HCI packet into a USB transfer buffer before enqueuing it on an endpoint. bt_hci_tx_sync_in() allocated that buffer from bt_hci_ep_pool, a fixed pool whose slots are only USBD_MAX_BULK_MPS bytes (64 on full-speed-only builds), and then performed net_buf_add_mem(buf, bt_buf->data, bt_buf->len) with no length check. HCI event and ACL buffers are sized by CONFIG_BT_BUF_EVT_RX_SIZE and CONFIG_BT_BUF_ACL_RX_SIZE and can be far larger, so the copy runs past the end of the 64-byte slot into the adjacent slots and into whatever follows the statically allocated pool.\n\nThe device runs the local Bluetooth controller in raw HCI mode (CONFIG_BT_HCI_RAW), so the oversized packets originate over the air. With the HCI buffer sizes recommended for full-featured controllers, an unauthenticated attacker within Bluetooth range can supply the overflowing bytes: a connected peer that negotiates Data Length Extension can send ACL fragments up to CONFIG_BT_CTLR_DATA_LENGTH_MAX bytes, and an attacker that merely broadcasts extended advertising data reaches the same path through LE Extended Advertising Report events, which the controller fragments only to CONFIG_BT_BUF_EVT_RX_SIZE. In the stock configuration the overflow is already reached without any radio traffic: the mandatory Read Supported Commands command-complete event is 70 bytes and overruns the 64-byte slot by six bytes on every host initialization.\n\nBecause net_buf_add_mem() validates tailroom only through an assertion unless CONFIG_NET_BUF_HARDENING is enabled, builds with CONFIG_ASSERT=n — the usual production setting — silently corrupt memory adjacent to the USB buffer pool with attacker-chosen contents, which on a target without memory protection between subsystems can lead to arbitrary code execution. Builds with assertions enabled fail the assertion instead and panic, giving a remotely triggerable denial of service. The fix introduces a separate bt_hci_tx_pool sized to MAX(BT_BUF_ACL_RX_SIZE, BT_BUF_EVT_RX_SIZE) for the controller-to-host direction while leaving the host-to-device pool at the endpoint packet size, which is already bounds-checked during reassembly.","published":"2026-10-23T20:17:28.000Z","lastModified":"2026-10-26T13:52:22.000Z","status":"Awaiting Analysis","sourceIdentifier":"vulnerabilities@zephyrproject.org","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-787"],"affected":[],"epss":{"score":0.00229,"percentile":0.13619,"date":"2026-10-26","history":[{"date":"2026-10-24","score":0.00383,"percentile":0.31193}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-23T20:17:28.000Z","detail":{"score":"8.8","severity":"HIGH","publishedAt":"2026-10-23T20:17:28.167Z"},"summary":"New CVE, high severity (CVSS 8.8)."}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/0419defd2391652edc27689d206fcd9c48439d4a","source":"vulnerabilities@zephyrproject.org"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w5px-w97v-c3hj","source":"vulnerabilities@zephyrproject.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-79982","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}