CVE-2026-11894— Double-free / use-after-free in Realtek BEE Bluetooth HCI driver `send()` error paths
Quick assessment
Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
zephyrproject zephyr是zephyrproject组织开源的一个面向物联网设备的实时操作系统。 zephyrproject zephyr 4.4.0至4.4.2之前版本存在资源管理错误漏洞，该漏洞源于Realtek BEE蓝牙HCI驱动在错误路径上未遵守缓冲区所有权契约，错误释放缓冲区，导致双重释放和释放后重用，可能造成设备崩溃或内存破坏。
Possible ATT&CK Techniques 2 AI
T1498 · Network Denial of Service T1059 · Command and Scripting InterpreterAffected Version Matrix 1
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| zephyrproject | zephyr | 4.4.0< 4.4.2 |
affected |
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I. Basic Information for CVE-2026-11894
Vulnerability Information
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Vulnerability Title
Double-free / use-after-free in Realtek BEE Bluetooth HCI driver `send()` error paths
Source: CVE Program / CVE List V5
Vulnerability Description
The Realtek BEE Bluetooth HCI driver's send callback, bt_hci_bee_send() in drivers/bluetooth/hci/hci_bee.c, violated the bt_hci_driver_api buffer-ownership contract. That contract requires the driver to consume (unref) the transmit net_buf only on success; on an error return the host caller retains ownership and unrefs the buffer itself. The pre-fix code routed all error paths through a shared cleanup label that unconditionally called net_buf_unref(buf) before returning the error code.
Because the host TX paths (in subsys/bluetooth/host/hci_core.c) unref the buffer again after send() returns an error, the buffer is freed twice: the driver returns it to its net_buf pool and the host then unrefs the already-freed buffer, corrupting the shared pool / underflowing the reference count (CWE-415). The same error branch additionally dereferenced buf->len inside a LOG_ERR call after the buffer had already been unref'd, a read of freed memory (CWE-416) that is compiled in at the default error log level.
The failing edges are reached when the controller's host-to-controller buffer allocation fails or the controller send fails (resource-exhaustion / IO conditions). A remote Bluetooth peer can push the device toward these conditions indirectly by driving heavy host transmit activity, at which point the double-free corrupts the host net_buf pool and most likely crashes the device, with residual potential for further memory corruption. The impact is confined to builds using this specific Realtek BEE HCI driver.
The fix returns early from each error path without unreffing and unrefs the buffer only on the success path, restoring the ownership contract and eliminating both the double-free and the use-after-free read.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
双重释放
Source: CVE Program / CVE List V5
Vulnerability Title
zephyrproject zephyr 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
zephyrproject zephyr是zephyrproject组织开源的一个面向物联网设备的实时操作系统。 zephyrproject zephyr 4.4.0至4.4.2之前版本存在资源管理错误漏洞，该漏洞源于Realtek BEE蓝牙HCI驱动在错误路径上未遵守缓冲区所有权契约，错误释放缓冲区，导致双重释放和释放后重用，可能造成设备崩溃或内存破坏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| zephyrproject | zephyr | 4.4.0 ~ 4.4.2 | - |
|
II. Public POCs for CVE-2026-11894
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Patches & Fixes for CVE-2026-11894 (2)
Same Patch Batch · zephyrproject · 2026-08-11 · 5 CVEs total
| CVE-2026-11893 | 5.9 MEDIUM | Double free / use-after-free in Bouffalo Lab HCI driver send() error paths (hci_bflb) |
| CVE-2026-12052 | 5.2 MEDIUM | Out-of-bounds write in USB CDC NCM control handler when host wLength is smaller than the r |
| CVE-2026-12051 | 4.6 MEDIUM | NULL pointer dereference in USB DFU device_next download handler (handle_download) |
| CVE-2026-11985 | 3.6 LOW | Cross-thread FPU register leak on ARM when FPU enabled without register sharing |
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V. Comments for CVE-2026-11894
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