CVE-2026-19738
- Source
- https://cve.org/CVERecord?id=CVE-2026-19738
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19738.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-19738
- Aliases
-
- GHSA-6mcj-5jw8-ff36
- Published
- 2026-10-11T17:15:04Z
- Modified
- 2026-10-13T07:01:33Z
- Severity
-
- 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- 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->node_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.
A 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.
In 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.
- Database specific
{ "cna_assigner": "zephyr", "cwe_ids": [ "CWE-401" ], "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19738.json", "unresolved_ranges": [ { "extracted_events": [ { "introduced": "3.4.0" }, { "fixed": "4.5.0" } ], "source": "AFFECTED_FIELD" } ] }- References
-
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19738.json
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6mcj-5jw8-ff36
- https://nvd.nist.gov/vuln/detail/CVE-2026-19738
- https://github.com/zephyrproject-rtos/zephyr/commit/fde17f2c3de0118f3796c2a83958ee4ce4b5efd6
- https://github.com/zephyrproject-rtos/zephyr
Affected packages
Git / github.com/zephyrproject-rtos/zephyr
Affected versions
v1.*
v2.*
v3.*
v4.*
zephyr-v1.*
zephyr-v2.*
zephyr-v3.*
Database specific
source
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19738.json"
vanir_signatures
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vanir_signatures_modified
"2026-10-13T07:01:33Z"