CVE-2025-38315 in Linux
Summary
by MITRE • 07/10/2025
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btintel: Check dsbr size from EFI variable
Since the size of struct btintel_dsbr is already known, we can just start there instead of querying the EFI variable size. If the final result doesn't match what we expect also fail. This fixes a stack buffer overflow when the EFI variable is larger than struct btintel_dsbr.
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Analysis
by VulDB Data Team • 12/07/2025
The vulnerability CVE-2025-38315 addresses a critical stack buffer overflow issue within the Linux kernel's Bluetooth subsystem, specifically affecting the btintel driver component. This flaw exists in the Intel Bluetooth controller initialization process where the driver attempts to read data from EFI variables containing device-specific boot records. The vulnerability stems from improper bounds checking when processing the btintel_dsbr structure, which is a well-defined data structure used to communicate device configuration parameters between the kernel and Intel Bluetooth hardware. The issue manifests when the driver queries EFI variables without properly validating the actual size of the data returned against the expected structure size, creating a potential attack surface for malicious actors to exploit buffer overflow conditions.
The technical implementation of this vulnerability involves the btintel driver's handling of EFI variable data during Bluetooth controller initialization. When the driver attempts to read the btintel_dsbr structure from EFI variables, it fails to validate that the actual data size matches the expected structure size. This mismatch can occur when EFI variables contain additional data beyond the standard btintel_dsbr structure, causing the driver to write beyond the allocated stack buffer boundaries. The flaw represents a classic buffer overflow condition that can be exploited to execute arbitrary code or cause system instability, particularly when the EFI variable size exceeds the sizeof(struct btintel_dsbr) boundary. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which occurs when a program writes data to a buffer located on the stack and exceeds the buffer's capacity.
The operational impact of CVE-2025-38315 extends beyond simple system crashes to potentially enable privilege escalation and persistent system compromise within embedded systems and devices that rely on Intel Bluetooth controllers. Systems running affected Linux kernel versions may experience unexpected behavior during Bluetooth initialization, leading to denial of service conditions or potential code execution. The vulnerability affects devices that utilize Intel Bluetooth hardware and boot through EFI firmware, making it particularly concerning for mobile devices, laptops, and embedded systems. Attackers could exploit this condition to inject malicious code into the kernel space, potentially gaining root privileges and establishing persistent backdoors. This vulnerability also aligns with ATT&CK technique T1068, which covers the exploitation of legitimate credentials and system access for privilege escalation purposes.
Mitigation strategies for CVE-2025-38315 require immediate kernel updates from vendors and system administrators to patch the vulnerable btintel driver implementation. The fix implemented in the Linux kernel ensures proper bounds checking by first verifying the EFI variable size against the known structure size before attempting to copy data into the stack buffer. This approach prevents the buffer overflow condition by ensuring that only data of the expected size is processed, eliminating the possibility of writing beyond allocated memory boundaries. Organizations should prioritize patching affected systems, particularly those running embedded Linux distributions or devices with Intel Bluetooth controllers that boot through EFI firmware. Additionally, system monitoring should be implemented to detect unusual Bluetooth initialization patterns or potential exploitation attempts, as the vulnerability may be leveraged as part of broader attack campaigns targeting embedded systems and IoT devices.