{"id":"UBUNTU-CVE-2026-79982","details":"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-\u003edata, bt_buf-\u003elen) 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. The 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. Because 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.","modified":"2026-10-27T04:17:57.741426351Z","published":"2026-10-26T00:00:00Z","upstream":["CVE-2026-79982"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-79982"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-79982"},{"type":"REPORT","url":"https://github.com/zephyrproject-rtos/zephyr/commit/0419defd2391652edc27689d206fcd9c48439d4a"},{"type":"REPORT","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-w5px-w97v-c3hj"}],"affected":[{"package":{"name":"zephyr","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1","3.1.2-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libzephyr4","binary_version":"3.1.2-1build1"},{"binary_version":"3.1.2-1build1","binary_name":"libzephyr4-krb5"},{"binary_name":"zephyr-clients","binary_version":"3.1.2-1build1"},{"binary_name":"zephyr-server","binary_version":"3.1.2-1build1"},{"binary_name":"zephyr-server-krb5","binary_version":"3.1.2-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1build1","3.1.2-1build2"],"ecosystem_specific":{"binaries":[{"binary_name":"libzephyr4","binary_version":"3.1.2-1build2"},{"binary_version":"3.1.2-1build2","binary_name":"libzephyr4-krb5"},{"binary_name":"zephyr-clients","binary_version":"3.1.2-1build2"},{"binary_version":"3.1.2-1build2","binary_name":"zephyr-server"},{"binary_version":"3.1.2-1build2","binary_name":"zephyr-server-krb5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1build3"],"ecosystem_specific":{"binaries":[{"binary_name":"libzephyr4","binary_version":"3.1.2-1build3"},{"binary_name":"libzephyr4-krb5","binary_version":"3.1.2-1build3"},{"binary_name":"zephyr-clients","binary_version":"3.1.2-1build3"},{"binary_version":"3.1.2-1build3","binary_name":"zephyr-server"},{"binary_version":"3.1.2-1build3","binary_name":"zephyr-server-krb5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1build3"],"ecosystem_specific":{"binaries":[{"binary_version":"3.1.2-1build3","binary_name":"libzephyr4"},{"binary_name":"libzephyr4-krb5","binary_version":"3.1.2-1build3"},{"binary_version":"3.1.2-1build3","binary_name":"zephyr-clients"},{"binary_name":"zephyr-server","binary_version":"3.1.2-1build3"},{"binary_version":"3.1.2-1build3","binary_name":"zephyr-server-krb5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1.1","3.1.2-1.1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libzephyr4","binary_version":"3.1.2-1.1build1"},{"binary_name":"libzephyr4-krb5","binary_version":"3.1.2-1.1build1"},{"binary_name":"zephyr-clients","binary_version":"3.1.2-1.1build1"},{"binary_version":"3.1.2-1.1build1","binary_name":"zephyr-server"},{"binary_version":"3.1.2-1.1build1","binary_name":"zephyr-server-krb5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-4"],"ecosystem_specific":{"binaries":[{"binary_name":"libzephyr4","binary_version":"3.1.2-4"},{"binary_name":"libzephyr4-krb5","binary_version":"3.1.2-4"},{"binary_name":"zephyr-clients","binary_version":"3.1.2-4"},{"binary_name":"zephyr-server","binary_version":"3.1.2-4"},{"binary_name":"zephyr-server-krb5","binary_version":"3.1.2-4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-79982.json"}},{"package":{"name":"zephyr","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/zephyr?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2-1.1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