Detections
Analytics
Linux Distros Unpatched Vulnerability : CVE-2026-81039
medium Nessus Plugin ID 372671
Synopsis
The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.Description
The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.- The Bluetooth host pre-allocates a bt_conn object (a reservation) from the fixed acl_conns[] pool for every connectable advertising set it starts, in le_adv_start_add_conn() in subsys/bluetooth/host/adv.c.
When an incoming peripheral connection completes, find_pending_connect() in subsys/bluetooth/host/hci_core.c looked that reservation up using only the identity and the peer address, with a directed-then-undirected fallback, and had no knowledge of which advertising set actually terminated. With CONFIG_BT_EXT_ADV_MAX_ADV_SET > 1, where the LE Enhanced Connection Complete event is cached until the LE Advertising Set Terminated event identifies the set, this lookup can return the reservation belonging to a different, still-running advertising set. The defect is reachable over the air by any adjacent device. If an application runs two connectable extended advertising sets on the same identity one undirected and one directed at a peer P (the common directed reconnect to a bonded central while still accepting new centrals pattern) a remote initiator whose address maps to P connecting on the undirected set causes the directed set's reservation to be consumed instead. The initiator address is chosen freely by the remote device and is not authenticated at link establishment, so no bonding, pairing or prior relationship is required to trigger the mis-attribution. The undirected set's own reservation is then stranded: its BT_ADV_ENABLED flag has already been cleared, and le_adv_stop_free_conn() the only path that returns a reservation to the pool is reached only for sets that are still enabled, so bt_le_ext_adv_stop() returns early and the object is never released. Each occurrence permanently consumes one CONFIG_BT_MAX_CONN slot until bt_disable() or reboot. In application patterns that restart the directed advertising set after each disconnect, an attacker can repeat the sequence until the pool is exhausted, after which connectable advertising fails with -ENOMEM and the device can no longer accept connections. As a side effect the directed set keeps advertising without a reservation, so a genuine connection on it is dropped by bt_hci_disconnect(). The impact is availability only; no memory corruption or information disclosure results, and configurations with a single advertising set are unaffected.
(CVE-2026-81039)
Note that Nessus relies on the presence of the package as reported by the vendor.
Solution
There is no known solution at this time.See Also
Plugin Details
Severity: Medium
ID: 372671
File Name: unpatched_CVE_2026_81039.nasl
Version: 1.1
Type: Local
Agent: unix
Family: Misc.
Published: 10/28/2026
Updated: 10/28/2026
Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus
Risk Information
VPR
Risk Factor: Low
Score: 3.2
Percentile: 50.39
CVSS v2
Risk Factor: Medium
Base Score: 5.5
Temporal Score: 4.7
Vector: CVSS2#AV:A/AC:L/Au:S/C:N/I:N/A:C
CVSS Score Source: CVE-2026-81039
CVSS v3
Risk Factor: Medium
Base Score: 4.3
Temporal Score: 4
Vector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Temporal Vector: CVSS:3.0/E:U/RL:U/RC:C
Vulnerability Information
CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.04:-:lts, cpe:/o:canonical:ubuntu_linux:26.10, p-cpe:/a:canonical:ubuntu_linux:zephyr
Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
Exploit Ease: No known exploits are available
Vulnerability Publication Date: 10/26/2026
Reference Information
CVE: CVE-2026-81039