{"api_version":"1","generated_at":"2026-10-18T17:22:22+00:00","cve":"CVE-2026-19739","urls":{"html":"https://cve.report/CVE-2026-19739","api":"https://cve.report/api/cve/CVE-2026-19739.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-19739","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-19739"},"summary":{"title":"Bluetooth LE controller leaks a retained RX node when an unexpected LL Control PDU arrives during a Connection Update","description":"The Bluetooth Link Layer control procedure code in subsys/bluetooth/controller/ll_sw/ull_llcp_conn_upd.c retains the received RX node while a Connection Update / Connection Parameter procedure waits for its instant, so the node can later carry the host notification (llcp_rx_node_retain(), which marks it NODE_RX_TYPE_RETAIN and thereby suppresses the normal recycling in ull.c). The default: arm of llcp_rp_cu_rx() and llcp_lp_cu_rx() — the \"invalid PDU, terminate the connection\" path — completed the procedure without releasing that retained node. llcp_rr_check_done() then dequeued and freed the procedure context with ctx->node_ref.rx still pointing at the retained node, dropping the last reference to it.\n\nA peer device in radio range can reach this without pairing, bonding, or encryption. Against a peripheral, the peer sends a well-formed LL_CONNECTION_UPDATE_IND with an instant a few connection events in the future (the node is retained and the procedure enters RP_CU_STATE_WAIT_INSTANT), then, before the instant is reached, sends any other LL Control PDU such as LL_LENGTH_REQ. ull_cp_rx() routes that PDU into the active remote Connection Update procedure, which takes the invalid-PDU path. The central role is reachable symmetrically after accepting an LL_CONNECTION_PARAM_REQ, and the local-procedure variant is reachable with LL_REJECT_IND.\n\nWith CONFIG_BT_CTLR_ASSERT_DEBUG enabled (its default), the resulting state violates the invariant asserted in llcp_rr_check_done(), so the two-PDU sequence produces an immediate fatal error in the controller. With those asserts disabled, each occurrence permanently loses one node from the controller's small fixed RX pool (sized from CONFIG_BT_CTLR_RX_BUFFERS, which defaults to 1); repeating the sequence across reconnections exhausts the pool, after which the link-layer receive path operates on a NULL node. The impact is an unauthenticated, remotely triggerable denial of service persisting until reboot; there is no memory-disclosure or memory-corruption consequence, since the leaked node simply becomes unreachable.","state":"PUBLISHED","assigner":"zephyr","published_at":"2026-10-11 18:16:59","updated_at":"2026-10-16 16:17:05"},"problem_types":["CWE-401","CWE-459","CWE-617","CWE-772","CWE-401 dos","CWE-459 dos","CWE-617 dos","CWE-772 dos"],"metrics":[{"version":"3.1","source":"vulnerabilities@zephyrproject.org","type":"Secondary","score":"6.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":6.5,"baseSeverity":"MEDIUM","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"6.5","severity":"MEDIUM","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","data":{"baseScore":6.5,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"}}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/7b600129faaba8bb26dd5cb3e8f17ed1cb41ea7f","name":"https://github.com/zephyrproject-rtos/zephyr/commit/7b600129faaba8bb26dd5cb3e8f17ed1cb41ea7f","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-84v8-vgp5-4vc9","name":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-84v8-vgp5-4vc9","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-19739","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19739","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"zephyrproject","product":"zephyr","version":"affected 3.4.0 4.5.0 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"19739","cve":"CVE-2026-19739","epss":"0.001020000","percentile":"0.008850000","score_date":"2026-10-12","updated_at":"2026-10-13 00:11:16"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-19739","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-10-16T15:50:37.226993Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-10-16T15:51:02.837Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"collectionURL":"https://github.com/zephyrproject-rtos/zephyr","defaultStatus":"unaffected","packageName":"zephyr","product":"zephyr","programFiles":["subsys/bluetooth/controller/ll_sw/ull_llcp_conn_upd.c"],"programRoutines":[{"name":"llcp_lp_cu_rx"},{"name":"llcp_rp_cu_rx"}],"vendor":"zephyrproject","versions":[{"lessThan":"4.5.0","status":"affected","version":"3.4.0","versionType":"semver"}]}],"descriptions":[{"lang":"en","value":"The Bluetooth Link Layer control procedure code in subsys/bluetooth/controller/ll_sw/ull_llcp_conn_upd.c retains the received RX node while a Connection Update / Connection Parameter procedure waits for its instant, so the node can later carry the host notification (llcp_rx_node_retain(), which marks it NODE_RX_TYPE_RETAIN and thereby suppresses the normal recycling in ull.c). The default: arm of llcp_rp_cu_rx() and llcp_lp_cu_rx() — the \"invalid PDU, terminate the connection\" path — completed the procedure without releasing that retained node. llcp_rr_check_done() then dequeued and freed the procedure context with ctx->node_ref.rx still pointing at the retained node, dropping the last reference to it.\n\nA peer device in radio range can reach this without pairing, bonding, or encryption. Against a peripheral, the peer sends a well-formed LL_CONNECTION_UPDATE_IND with an instant a few connection events in the future (the node is retained and the procedure enters RP_CU_STATE_WAIT_INSTANT), then, before the instant is reached, sends any other LL Control PDU such as LL_LENGTH_REQ. ull_cp_rx() routes that PDU into the active remote Connection Update procedure, which takes the invalid-PDU path. The central role is reachable symmetrically after accepting an LL_CONNECTION_PARAM_REQ, and the local-procedure variant is reachable with LL_REJECT_IND.\n\nWith CONFIG_BT_CTLR_ASSERT_DEBUG enabled (its default), the resulting state violates the invariant asserted in llcp_rr_check_done(), so the two-PDU sequence produces an immediate fatal error in the controller. With those asserts disabled, each occurrence permanently loses one node from the controller's small fixed RX pool (sized from CONFIG_BT_CTLR_RX_BUFFERS, which defaults to 1); repeating the sequence across reconnections exhausts the pool, after which the link-layer receive path operates on a NULL node. The impact is an unauthenticated, remotely triggerable denial of service persisting until reboot; there is no memory-disclosure or memory-corruption consequence, since the leaked node simply becomes unreachable."}],"metrics":[{"cvssV3_1":{"baseScore":6.5,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-401","description":"dos","lang":"en","type":"CWE"},{"cweId":"CWE-459","description":"dos","lang":"en","type":"CWE"},{"cweId":"CWE-617","description":"dos","lang":"en","type":"CWE"},{"cweId":"CWE-772","description":"dos","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-11T17:15:06.540Z","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr"},"references":[{"name":"Fix commit","tags":["patch"],"url":"https://github.com/zephyrproject-rtos/zephyr/commit/7b600129faaba8bb26dd5cb3e8f17ed1cb41ea7f"},{"name":"GHSA-84v8-vgp5-4vc9","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-84v8-vgp5-4vc9"}],"title":"Bluetooth LE controller leaks a retained RX node when an unexpected LL Control PDU arrives during a Connection Update","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","assignerShortName":"zephyr","cveId":"CVE-2026-19739","datePublished":"2026-10-11T17:15:06.540Z","dateReserved":"2026-08-13T13:46:31.915Z","dateUpdated":"2026-10-16T15:51:02.837Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-11 18:16:59","lastModifiedDate":"2026-10-16 16:17:05","problem_types":["CWE-401","CWE-459","CWE-617","CWE-772","CWE-401 dos","CWE-459 dos","CWE-617 dos","CWE-772 dos"],"metrics":{"cvssMetricV31":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":6.5,"baseSeverity":"MEDIUM","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-16T15:50:37.226993Z","id":"CVE-2026-19739","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"19739","Ordinal":"1","Title":"Bluetooth LE controller leaks a retained RX node when an unexpec","CVE":"CVE-2026-19739","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"19739","Ordinal":"1","NoteData":"The Bluetooth Link Layer control procedure code in subsys/bluetooth/controller/ll_sw/ull_llcp_conn_upd.c retains the received RX node while a Connection Update / Connection Parameter procedure waits for its instant, so the node can later carry the host notification (llcp_rx_node_retain(), which marks it NODE_RX_TYPE_RETAIN and thereby suppresses the normal recycling in ull.c). The default: arm of llcp_rp_cu_rx() and llcp_lp_cu_rx() — the \"invalid PDU, terminate the connection\" path — completed the procedure without releasing that retained node. llcp_rr_check_done() then dequeued and freed the procedure context with ctx->node_ref.rx still pointing at the retained node, dropping the last reference to it.\n\nA peer device in radio range can reach this without pairing, bonding, or encryption. Against a peripheral, the peer sends a well-formed LL_CONNECTION_UPDATE_IND with an instant a few connection events in the future (the node is retained and the procedure enters RP_CU_STATE_WAIT_INSTANT), then, before the instant is reached, sends any other LL Control PDU such as LL_LENGTH_REQ. ull_cp_rx() routes that PDU into the active remote Connection Update procedure, which takes the invalid-PDU path. The central role is reachable symmetrically after accepting an LL_CONNECTION_PARAM_REQ, and the local-procedure variant is reachable with LL_REJECT_IND.\n\nWith CONFIG_BT_CTLR_ASSERT_DEBUG enabled (its default), the resulting state violates the invariant asserted in llcp_rr_check_done(), so the two-PDU sequence produces an immediate fatal error in the controller. With those asserts disabled, each occurrence permanently loses one node from the controller's small fixed RX pool (sized from CONFIG_BT_CTLR_RX_BUFFERS, which defaults to 1); repeating the sequence across reconnections exhausts the pool, after which the link-layer receive path operates on a NULL node. The impact is an unauthenticated, remotely triggerable denial of service persisting until reboot; there is no memory-disclosure or memory-corruption consequence, since the leaked node simply becomes unreachable.","Type":"Description","Title":"Bluetooth LE controller leaks a retained RX node when an unexpec"}]}}}