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CVE-2026-11893: use-after-free in zephyrproject zephyr

0
Medium
VulnerabilityCVE-2026-11893cvecve-2026-11893
Published: 08/11/2026 (08/11/2026, 04:42:39 UTC)
Source: CVE Database V5
Vendor/Project: zephyrproject
Product: zephyr

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.

CVSS v3.1

Score 5.9medium

Attack Vector
Adjacent Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected software

GitHub Actionsmore threats →cve
zephyr
pkg:github/zephyr
Affected versions
>=4.4.0 <4.4.2

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

Technical Details

Data Version
5.2
Assigner Short Name
zephyr
Date Reserved
2026-06-10T15:13:51.139Z
Cvss Version
3.1
State
PUBLISHED
Remediation Level
null

Threat ID: 6a7aaf24bf8831d53928ad67

Added to database: 08/11/2026, 05:12:04 UTC

Last updated: 08/11/2026, 05:12:04 UTC

Views: 1

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