Zephyr Project up to 4.4.1 Bluetooth HCI driver hci_bflb.c bt_bflb_send use after free

Summaryinfo

A vulnerability categorized as problematic has been discovered in Zephyr Project Zephyr up to 4.4.1. This impacts the function bt_bflb_send of the file drivers/bluetooth/hci/hci_bflb.c of the component Bluetooth HCI driver. The manipulation results in use after free. This vulnerability is known as CVE-2026-11893. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as problematic has been found in Zephyr Project Zephyr up to 4.4.1. Affected is the function bt_bflb_send of the file drivers/bluetooth/hci/hci_bflb.c of the component Bluetooth HCI driver. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on integrity, and availability. CVE summarizes:

The Bluetooth HCI driver for Bouffalo Lab on-chip BLE controllers (BL60x/BL70x/BL61x), bt_bflb_send() in drivers/bluetooth/hci/hci_bflb.c, violates the bt_hci_driver_api.send() buffer-ownership contract. That contract (documented at include/zephyr/drivers/bluetooth.h) requires the buffer reference to be consumed only on success; on error the caller still owns the reference and unrefs it. The driver instead routed all error paths through a shared label that unconditionally called net_buf_unref(buf) before returning the error code, consuming the buffer on failure as well. When send() returns an error, the host TX path (send_buf() in subsys/bluetooth/host/conn.c) unrefs the same buffer again, believing it still owns it. This double-unref over-decrements the net_buf reference count. Because the buffer is a TX fragment whose destroy callback also decrements its still-queued parent buffer, the parent is freed prematurely while reachable on the connection TX queue, producing a use-after-free and corruption of the shared net_buf pool rather than a benign leak. The error conditions are on the host-to-controller transmit path (controller send failure, or an unsupported H:4 packet type), so they are not driven directly by attacker-supplied radio bytes; a remote/adjacent peer can influence them only indirectly, e.g. by inducing controller TX failures under heavy link load. The consequence when reached is BLE-stack denial of service (crash / pool corruption) with possible further memory corruption, bounded to devices using one of these Bouffalo Lab on-chip controllers.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-11893 since 06/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit.

Upgrading to version 4.4.2 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.4.0
• 4.4.1

CPE 2.3info

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CPE 2.2info

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