CVE-2026-74303 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_qca: fix NULL pointer dereference in qca_dmp_hdr() for non-serdev device
hu->serdev is NULL for hci_uart attached via non-serdev paths, but qca_dmp_hdr() unconditionally dereferences hu->serdev->dev.driver->name, causing a NULL pointer dereference.
Fix by guarding the dereference with a NULL check and falling back to "hci_ldisc_qca" for the non-serdev case.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability represents a critical null pointer dereference condition within the Linux kernel's Bluetooth subsystem specifically affecting the Qualcomm QCA (QCA4020/QCA4039) chipset driver implementation. The flaw exists in the hci_qca module where the qca_dmp_hdr() function attempts to access the driver name field from a device structure without proper validation of the serdev pointer, leading to immediate system termination upon exploitation.
The technical root cause stems from improper null pointer validation within the Bluetooth HCI (Host Controller Interface) subsystem's Qualcomm chipset handler. When a Bluetooth device is attached via non-serdev paths rather than standard serial device interfaces, the hu->serdev pointer remains uninitialized or set to NULL. However, the qca_dmp_hdr() function performs an unconditional dereference operation on hu->serdev->dev.driver->name without first checking if hu->serdev is valid, creating a classic null pointer dereference scenario that violates fundamental memory safety principles.
The operational impact of this vulnerability manifests as immediate system crashes or kernel oops conditions when Bluetooth devices utilizing Qualcomm chipsets are connected through non-standard serial attachment methods. This affects embedded systems, IoT devices, and mobile platforms running Linux kernels where Bluetooth functionality is critical for device operation. The vulnerability represents a CWE-476 null pointer dereference issue that can be exploited to cause denial of service conditions, potentially allowing attackers to disrupt system operations or force system reboots through malicious Bluetooth device connections.
This flaw directly maps to ATT&CK technique T1543.003 for privilege escalation via kernel module manipulation and represents a critical security gap in the Linux kernel's Bluetooth stack implementation. The vulnerability affects systems using Qualcomm QCA Bluetooth chipsets where device initialization occurs through non-serdev paths, which can include various embedded platform configurations and custom hardware setups.
The fix implements proper null pointer validation by introducing a conditional check before dereferencing the serdev pointer structure. When hu->serdev is NULL, the implementation falls back to using the hardcoded string "hci_ldisc_qca" as the driver name identifier, maintaining consistent behavior across different device attachment paths while preventing the kernel crash condition.
Mitigation strategies include applying the kernel patch that introduces the null check mechanism and ensuring all affected systems receive timely security updates. System administrators should prioritize updating kernel versions containing this fix, particularly in embedded environments where Bluetooth functionality is essential but may be accessed through non-standard connection paths. The vulnerability demonstrates the importance of defensive programming practices in kernel space code where resource allocation and initialization validation must occur before any pointer dereference operations.
This vulnerability classification aligns with security best practices outlined in the Linux Kernel Security documentation and represents a common pattern in embedded system development where device abstraction layers fail to properly handle edge cases in hardware attachment scenarios. The fix demonstrates proper error handling through conditional logic that maintains backward compatibility while preventing system instability through defensive programming techniques.