CVE-2025-20680: Mediatek Nbiot SDK Privilege Escalation

CVE-2025-20680 Overview

CVE-2025-20680 is a critical out-of-bounds write vulnerability in the MediaTek Bluetooth driver caused by an incorrect bounds check. This heap-based buffer overflow (CWE-122) affects multiple MediaTek wireless chipsets and the NB-IoT SDK. The vulnerability could allow an attacker to achieve local escalation of privilege with user execution privileges, without requiring any user interaction.

Critical Impact

This vulnerability enables local privilege escalation through a heap-based buffer overflow in the Bluetooth driver, potentially allowing attackers to gain elevated system access on affected devices using MediaTek wireless chipsets.

Affected Products

• MediaTek NB-IoT SDK
• MediaTek MT7902 Wireless Chipset
• MediaTek MT7920 Wireless Chipset
• MediaTek MT7921 Wireless Chipset
• MediaTek MT7922 Wireless Chipset
• MediaTek MT7925 Wireless Chipset
• MediaTek MT7927 Wireless Chipset

Discovery Timeline

• 2025-07-08 - CVE-2025-20680 published to NVD
• 2025-07-14 - Last updated in NVD database

Technical Details for CVE-2025-20680

Vulnerability Analysis

This vulnerability is classified as a heap-based buffer overflow (CWE-122) residing in the MediaTek Bluetooth driver. The flaw occurs due to an incorrect bounds check when processing data, allowing writes beyond the allocated buffer boundaries. The vulnerability is network-accessible and requires no authentication or user interaction to exploit, making it particularly dangerous in enterprise environments where affected MediaTek wireless chipsets are deployed.

The affected MT79xx series chipsets are commonly found in laptops, IoT devices, and embedded systems, extending the potential attack surface across consumer and enterprise hardware. Successful exploitation could allow an attacker with user-level access to escalate privileges to a higher level, potentially gaining kernel-level access to the system.

Root Cause

The root cause of CVE-2025-20680 is an incorrect bounds check within the Bluetooth driver code. When processing incoming data, the driver fails to properly validate the size of input before writing to a heap-allocated buffer. This improper input validation allows an attacker to supply specially crafted data that exceeds the buffer boundaries, resulting in heap memory corruption. The flaw is tracked internally by MediaTek as Patch ID: WCNCR00418044 and Issue ID: MSV-3482.

Attack Vector

The attack vector for this vulnerability is network-based, meaning an attacker could potentially trigger the vulnerability remotely through Bluetooth communications. The attack does not require any privileges on the target system and can be executed without user interaction. An attacker would craft malicious Bluetooth packets designed to trigger the incorrect bounds check, causing an out-of-bounds write to heap memory. By carefully controlling the overflow data, an attacker could potentially overwrite adjacent memory structures to achieve code execution or escalate privileges.

The exploitation scenario would involve the attacker being within Bluetooth range of a vulnerable device, sending specially crafted packets that trigger the buffer overflow, and leveraging the memory corruption to gain elevated privileges on the target system.

Detection Methods for CVE-2025-20680

Indicators of Compromise

• Unusual Bluetooth driver crashes or system instability related to wireless subsystems
• Unexpected privilege escalation events or unauthorized administrative access
• Anomalous Bluetooth traffic patterns or connection attempts from unknown sources
• System logs showing heap corruption or memory access violations in Bluetooth driver components

Detection Strategies

• Monitor system logs for Bluetooth driver errors, crashes, or memory corruption events
• Implement endpoint detection and response (EDR) solutions to detect privilege escalation attempts
• Deploy network intrusion detection systems (NIDS) configured to identify anomalous Bluetooth protocol traffic
• Use SentinelOne Singularity platform to detect behavioral indicators of exploitation attempts targeting kernel drivers

Monitoring Recommendations

• Enable verbose logging for Bluetooth subsystem components on affected devices
• Configure alerting for kernel-mode driver crashes or unexpected terminations
• Monitor for processes gaining elevated privileges through non-standard escalation paths
• Track driver and firmware versions across the fleet to identify unpatched systems

How to Mitigate CVE-2025-20680

Immediate Actions Required

• Apply the MediaTek security patch referenced in the MediaTek Security Bulletin - July 2025
• Inventory all devices using affected MediaTek MT79xx series wireless chipsets
• Prioritize patching for internet-facing and high-value systems
• Consider disabling Bluetooth functionality on critical systems until patches are applied

Patch Information

MediaTek has released security patches to address this vulnerability as part of their July 2025 security bulletin. The fix is tracked under Patch ID: WCNCR00418044. Organizations should obtain updated drivers from their device manufacturers or directly from MediaTek's security advisory. Refer to the MediaTek Security Bulletin - July 2025 for specific patch availability and deployment instructions.

Workarounds

• Disable Bluetooth functionality on affected devices where it is not required for business operations
• Implement network segmentation to limit Bluetooth exposure in sensitive environments
• Enable application allowlisting and privilege restriction policies to limit the impact of potential exploitation
• Deploy endpoint protection solutions capable of detecting and blocking privilege escalation attempts

# Example: Disable Bluetooth service on Linux systems with affected chipsets
sudo systemctl stop bluetooth
sudo systemctl disable bluetooth

# Verify Bluetooth service is disabled
systemctl status bluetooth