5.9
MEDIUM CVSS 3.1
CVE-2026-11893
Double free / use-after-free in Bouffalo Lab HCI driver send() error paths (hci_bflb)
Description

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.

INFO

Published Date :

Aug. 11, 2026, 5:17 a.m.

Last Modified :

Aug. 11, 2026, 5:17 a.m.

Remotely Exploit :

No
Affected Products

The following products are affected by CVE-2026-11893 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Zephyrproject zephyr
2 Zephyrproject zephyr
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM e2e69745-5e70-4e92-8431-deb5529a81ad
CVSS 3.1 MEDIUM [email protected]
Solution
Fix a double-unref bug in the Bluetooth HCI driver for Bouffalo Lab controllers.
  • Apply the patch to drivers/bluetooth/hci/hci_bflb.c.
  • Update the Bluetooth HCI driver.
  • Ensure buffer ownership contract is respected.
  • Test thoroughly for memory corruption.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-11893.

URL Resource
https://github.com/zephyrproject-rtos/zephyr/commit/76d92d502b30218aaf11cbbe1be180a317627bb9
https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-ph42-6rqx-728c
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-11893 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-11893 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-11893 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2026-11893 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by [email protected]

    Aug. 11, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'zephyrproject', 'product': 'zephyr', 'versions': [{'status': 'affected', 'version': '4.4.0', 'lessThan': '4.4.2', 'versionType': 'semver'}], 'packageName': 'zephyr', 'programFiles': ['drivers/bluetooth/hci/hci_bflb.c'], 'collectionURL': 'https://github.com/zephyrproject-rtos/zephyr', 'defaultStatus': 'unaffected'}]
    Added Description 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.
    Added CVSS V3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
    Added CWE CWE-415
    Added Reference https://github.com/zephyrproject-rtos/zephyr/commit/76d92d502b30218aaf11cbbe1be180a317627bb9
    Added Reference https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-ph42-6rqx-728c
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.