{"id":"CVE-2026-19738","summary":"Retained RX node leak and reachable assertion in Bluetooth Controller CIS Create procedures","details":"The Bluetooth Link Layer Control Procedure (LLCP) implementation for Connected Isochronous Stream (CIS) creation retains an RX node (ctx-\u003enode_ref.rx, marked NODE_RX_TYPE_RETAIN) so it can later be reused as the host notification — on the peripheral while awaiting the Host's reply to an LL_CIS_REQ, and on the central for the whole duration of a locally initiated CIS Create. In subsys/bluetooth/controller/ll_sw/ull_llcp_cc.c, the \"invalid PDU received\" paths of llcp_rp_cc_rx() and llcp_lp_cc_rx() terminated the connection and completed the procedure without releasing that retained node, breaking the invariant checked in llcp_lr_check_done() and llcp_rr_check_done() and orphaning the node's memory.\n\nA peer device within radio range can reach this with a single extra LL Control PDU on an unauthenticated, unencrypted ACL link. Against a peripheral, the attacker sends a valid LL_CIS_REQ and then, before the Host replies, any unrelated LL Control PDU (for example LL_VERSION_IND), which ull_cp_rx() routes into the active remote procedure. Against a central performing a CIS Create, a malicious peripheral answers with LL_UNKNOWN_RSP for CIS_REQ, which is dispatched into the active local procedure. No pairing, encryption or user interaction is required; the code is compiled in when CONFIG_BT_CTLR_PERIPHERAL_ISO or CONFIG_BT_CTLR_CENTRAL_ISO is enabled.\n\nIn default builds (CONFIG_BT_CTLR_ASSERT_DEBUG is default y) the retained-node assertion fires immediately, producing a controller fatal error and, typically, a system reset from one injected PDU. With the development assertions disabled, each attempt permanently loses one node from the controller's small LL notification pool (LL_PDU_RX_CNT, 2 * CONFIG_BT_CTLR_LLCP_CONN) together with its memq_link_t; repeating the connect-attack-reconnect cycle exhausts the pool, after which notification allocation always fails, RX flow control stalls, and the non-disableable LL_ASSERT_ERR() in llcp_lp_cc_flush() faults. The impact is limited to availability — the leaked node is orphaned, never reused or double-freed — and recovery requires a reboot.","aliases":["GHSA-6mcj-5jw8-ff36"],"modified":"2026-10-13T07:01:33.386796679Z","published":"2026-10-11T17:15:04.970Z","database_specific":{"unresolved_ranges":[{"extracted_events":[{"introduced":"3.4.0"},{"fixed":"4.5.0"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"zephyr","cwe_ids":["CWE-401"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19738.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19738.json"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6mcj-5jw8-ff36"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19738"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/fde17f2c3de0118f3796c2a83958ee4ce4b5efd6"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"0"},{"fixed":"fde17f2c3de0118f3796c2a83958ee4ce4b5efd6"}],"database_specific":{"source":"REFERENCES"}}],"versions":["v4.4.0","v4.4.0-rc3","v4.4.0-rc2","v4.4.0-rc1","v4.3.0","v4.3.0-rc3","v4.3.0-rc2","v4.3.0-rc1","v4.2.0","v4.2.0-rc3","v4.2.0-rc2","v4.2.0-rc1","v4.1.0","v4.1.0-rc3","v4.1.0-rc2","v4.1.0-rc1","v4.0.0","v4.0.0-rc3","v4.0.0-rc2","v4.0.0-rc1","v3.7.0","v3.7.0-rc3","v3.7.0-rc2","v3.7.0-rc1","v3.6.0","v3.6.0-rc3","v3.6.0-rc2","v3.6.0-rc1","zephyr-v3.5.0","v3.5.0","v3.5.0-rc3","v3.5.0-rc2","v3.5.0-rc1","zephyr-v3.4.0","v3.4.0","v3.4.0-rc3","v3.4.0-rc2","v3.4.0-rc1","zephyr-v3.3.0","v3.3.0","v3.3.0-rc3","v3.3.0-rc2","v3.3.0-rc1","zephyr-v3.2.0","v3.2.0","v3.2.0-rc3","v3.2.0-rc2","v3.2.0-rc1","zephyr-v3.1.0","v3.1.0","v3.1.0-rc3","v3.1.0-rc2","v3.1.0-rc1","zephyr-v3.0.0","v3.0.0","v3.0.0-rc3","v3.0.0-rc2","v3.0.0-rc1","v2.7.99","v2.7.0-rc3","v2.7.0-rc2","v2.7.0-rc1","zephyr-v2.6.0","v2.6.0","v2.6.0-rc3","v2.6.0-rc2","v2.6.0-rc1","zephyr-v2.5.0","v2.5.0","v2.5.0-rc4","v2.5.0-rc3","v2.5.0-rc2","v2.5.0-rc1","zephyr-v2.4.0","v2.4.0","v2.4.0-rc3","v2.4.0-rc2","v2.4.0-rc1","zephyr-v2.3.0","v2.3.0","v2.3.0-rc2","v2.3.0-rc1","zephyr-v2.1.0","v2.1.0","zephyr-v2.2.0","v2.2.0","v2.2.0-rc3","v2.2.0-rc2","v2.2.0-rc1","v2.1.0-rc3","v2.1.0-rc2","v2.1.0-rc1","zephyr-v2.0.0","v2.0.0","v2.0.0-rc3","v2.0.0-rc2","v2.0.0-rc1","zephyr-v1.14.0","v1.14.0","v1.14.0-rc3","v1.14.0-rc2","v1.14.0-rc1","zephyr-v1.13.0","v1.13.0","v1.13.0-rc3","v1.13.0-rc2","v1.13.0-rc1","zephyr-v1.12.0","v1.12.0","v1.12.0-rc3","v1.12.0-rc2","v1.12.0-rc1","zephyr-v1.11.0","v1.11.0","v1.11.0-rc3","v1.11.0-rc2","v1.11.0-rc1","zephyr-v1.10.0","v1.10.0","v1.10.0-rc3","v1.10.0-rc2","v1.10.0-rc1","zephyr-v1.9.0","v1.9.0","v1.9.0-rc4","v1.9.0-rc3","v1.9.0-rc2","v1.9.0-rc1","v1.8.99","zephyr-v1.5.0","v1.5.0","v1.7.99","v1.6.99","v1.5.0-rc4","v1.5.0-rc3","v1.5.0-rc2","v1.5.0-rc1","v1.5.0-rc0","zephyr-v1.4.0","v1.4.0","v1.4.0-rc3","v1.4.0-rc2","v1.4.0-rc1","zephyr-v1.3.0","v1.3.0","v1.3.0-rc2","v1.3.0-rc1","zephyr-v1.2.0","v1.2.0","v1.2.0-rc2","v1.2.0-rc1","zephyr-v1.1.0","v1.1.0","v1.1.0-rc1","zephyr-v1.0.0","v1.0.0"],"database_specific":{"vanir_signatures":[{"source":"https://github.com/zephyrproject-rtos/zephyr/commit/fde17f2c3de0118f3796c2a83958ee4ce4b5efd6","target":{"file":"subsys/bluetooth/controller/ll_sw/ull_llcp_cc.c"},"deprecated":false,"digest":{"line_hashes":["135035397242682923938940796715808736887","316605279232163874252627673590778793588","91980403134506916960688919468744312587","328547317025466234453595596329886374721","43191210951706079702434836035993313191","95431937156492165289850287182280951177","88876095488478896349485344239203440478","169083117063003347493621596946790968389"],"threshold":0.9},"id":"CVE-2026-19738-6b5b6364","signature_type":"Line","signature_version":"v1"},{"target":{"file":"subsys/bluetooth/controller/ll_sw/ull_llcp_cc.c","function":"llcp_rp_cc_rx"},"deprecated":false,"digest":{"function_hash":"51729755454229116008165208409422380583","length":638},"id":"CVE-2026-19738-6ce1f8f6","signature_type":"Function","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/fde17f2c3de0118f3796c2a83958ee4ce4b5efd6"},{"signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/fde17f2c3de0118f3796c2a83958ee4ce4b5efd6","target":{"function":"llcp_lp_cc_rx","file":"subsys/bluetooth/controller/ll_sw/ull_llcp_cc.c"},"deprecated":false,"digest":{"length":539,"function_hash":"51836658487746152832899748647758249801"},"id":"CVE-2026-19738-a7731fcb","signature_type":"Function"}],"vanir_signatures_modified":"2026-10-13T07:01:33Z","source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19738.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}