{"id":"CVE-2026-19739","aliases":[],"cve":{"records":[{"id":"CVE-2026-19739","source":"zephyr","state":"PUBLISHED","reasons":[],"replacements":[],"disputed":false,"unsupportedWhenAssigned":false,"reserved":"2026-08-13T13:46:31.915Z","published":"2026-10-11T17:15:06.540Z","modified":"2026-11-04T05:00:55.331Z"}],"publishers":[{"name":"zephyr","role":"CNA","organizationId":"e2e69745-5e70-4e92-8431-deb5529a81ad","modified":"2026-11-04T05:00:55.331Z"},{"name":"CISA-ADP","role":"ADP","organizationId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","modified":"2026-10-16T15:51:02.837Z"}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/7b600129faaba8bb26dd5cb3e8f17ed1cb41ea7f","tags":["patch"],"source":"zephyr"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-84v8-vgp5-4vc9","tags":[],"source":"zephyr"}],"weaknesses":[{"id":"CWE-401","description":"dos","source":"zephyr"},{"id":"CWE-459","description":"dos","source":"zephyr"},{"id":"CWE-617","description":"dos","source":"zephyr"},{"id":"CWE-772","description":"dos","source":"zephyr"}],"applicability":[],"prioritization":[{"source":"CISA-ADP","type":"SSVC","role":"CISA Coordinator","timestamp":"2026-10-16T15:50:37.226993Z","decisions":[{"name":"Exploitation","value":"none"},{"name":"Automatable","value":"no"},{"name":"Technical Impact","value":"partial"}]}]},"title":"Bluetooth LE controller leaks a retained RX node when an unexpected LL Control PDU arrives during a Connection Update","titleSource":"zephyr","descriptionSource":"zephyr","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.","score":6.5,"severity":"medium","published":"2026-10-11T17:15:06.540Z","modified":"2026-11-04T05:00:55.331Z","withdrawn":false,"knownExploited":false,"affected":[],"products":[{"vendor":"zephyrproject","name":"zephyr","platforms":[],"versions":[{"version":"3.4.0","status":"affected","lessThan":"4.3.2","versionType":"semver"},{"version":"4.4.0","status":"affected","lessThan":"4.5.0","versionType":"semver"}],"defaultStatus":"unaffected","cpes":[],"source":"zephyr","url":"https://www.cve.org/CVERecord?id=CVE-2026-19739"}],"remediation":[],"references":["https://github.com/zephyrproject-rtos/zephyr/commit/7b600129faaba8bb26dd5cb3e8f17ed1cb41ea7f","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-84v8-vgp5-4vc9"],"sources":[{"name":"CVE","id":"CVE-2026-19739","modified":"2026-11-04T05:00:55.331Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-19739"}],"assessments":[{"source":"zephyr","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":6.5}],"sourceAffected":[],"observedAt":"2026-11-04T05:16:12.072Z","kev":{"status":"not-listed","checkedAt":"2026-11-14T23:50:31.991Z"},"coverage":[{"source":"NVD","status":"available","checkedAt":"2026-11-04T05:50:39.285Z","attemptedAt":"2026-11-04T05:50:39.285Z"},{"source":"GHSA","status":"no-result","checkedAt":"2026-11-04T05:50:39.546Z","attemptedAt":"2026-11-04T05:50:39.546Z"},{"source":"EUVD","status":"available","checkedAt":"2026-11-04T05:50:39.837Z","attemptedAt":"2026-11-04T05:50:39.837Z"},{"source":"EPSS","status":"available","checkedAt":"2026-11-04T05:50:39.236Z","attemptedAt":"2026-11-04T05:50:39.236Z"}],"evidence":[{"source":"FIRST EPSS","id":"CVE-2026-19739","url":"https://www.first.org/epss/","probability":0.00102,"percentile":0.00924,"date":"2026-11-03","checkedAt":"2026-11-04T05:50:39.236Z"},{"source":"NVD","id":"CVE-2026-19739","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19739","modified":"2026-11-04T05:18:50.590","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","checkedAt":"2026-11-04T05:50:39.285Z"},{"source":"ENISA EUVD","id":"EUVD-2026-97108","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-97108","modified":"Oct 16, 2026, 3:51:02 PM","score":6.5,"vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","checkedAt":"2026-11-04T05:50:39.837Z"}],"aiSummary":{"text":"Zephyr Bluetooth LE controller versions 3.4.0 to 4.3.2 and 4.4.0 to 4.5.0 have a denial of service weakness. A peer device can trigger this without pairing or encryption by sending specific LL Control PDUs. The impact is a remotely triggerable denial of service until reboot.","model":"@cf/meta/llama-3.3-70b-instruct-fp8-fast","generatedAt":"2026-11-04T05:26:07.245Z","sources":[{"name":"CVE","url":"https://www.cve.org/CVERecord?id=CVE-2026-19739"}]}}