CVE-2025-20680 Overview
CVE-2025-20680 is an out-of-bounds write vulnerability in the MediaTek Bluetooth driver caused by an incorrect bounds check. The flaw affects the MediaTek NB-IoT SDK and multiple Wi-Fi/Bluetooth combo chipsets, including the MT7902, MT7920, MT7921, MT7922, MT7925, and MT7927. According to the MediaTek advisory, exploitation can lead to local escalation of privilege. The issue is tracked as Patch ID WCNCR00418044 and Issue ID MSV-3482. The vulnerability is classified under CWE-122: Heap-based Buffer Overflow.
Critical Impact
An attacker with local user-level execution can trigger an out-of-bounds write in the Bluetooth driver and escalate privileges without user interaction.
Affected Products
- MediaTek NB-IoT SDK
- MediaTek MT7902, MT7920, MT7921, MT7922 chipsets
- MediaTek MT7925, MT7927 chipsets
Discovery Timeline
- 2025-07-08 - CVE-2025-20680 published to NVD
- 2025-07-08 - MediaTek publishes July 2025 Product Security Bulletin
- 2025-07-14 - Last updated in NVD database
Technical Details for CVE-2025-20680
Vulnerability Analysis
The vulnerability resides in the MediaTek Bluetooth driver and is the result of an incorrect bounds check before a memory write operation. Because the driver fails to validate buffer length correctly, attacker-controlled data can be written beyond the bounds of a heap-allocated buffer. The bug is classified as CWE-122: Heap-based Buffer Overflow. Successful exploitation results in local privilege escalation while the attacker holds only user-level execution privileges. No user interaction is required to trigger the corruption.
Root Cause
The root cause is an incorrect bounds check in the Bluetooth driver path. The driver compares an attacker-influenced length value against a buffer boundary using flawed logic, allowing the write operation to proceed past the allocated region. This out-of-bounds write corrupts adjacent heap metadata or driver structures within the kernel address space. MediaTek tracks the fix internally as Patch ID WCNCR00418044 and Issue ID MSV-3482.
Attack Vector
A local attacker running unprivileged code on an affected device invokes the vulnerable Bluetooth driver interface. By supplying crafted input that bypasses the faulty bounds check, the attacker triggers the heap write primitive. Controlled corruption of kernel structures can be used to redirect execution or elevate the process to a higher privilege context. Because the flaw lives in chipset driver code shipped to multiple OEMs, every device integrating the affected NB-IoT SDK or listed combo chipsets inherits the exposure.
No verified public exploit code or proof-of-concept is available at the time of writing. Refer to the MediaTek Product Security Bulletin - July 2025 for vendor-supplied technical details.
Detection Methods for CVE-2025-20680
Indicators of Compromise
- Unexpected kernel panics, Bluetooth stack crashes, or bt_stack driver fault entries in dmesg and device logs.
- Local processes spawning elevated child processes after interacting with Bluetooth HCI interfaces.
- Anomalous activity from non-privileged users immediately following Bluetooth pairing or scanning operations.
Detection Strategies
- Inventory firmware and chipset revisions across managed devices to identify MediaTek MT79xx and NB-IoT SDK builds lacking Patch ID WCNCR00418044.
- Monitor endpoint telemetry for unauthorized privilege transitions originating from processes that hold Bluetooth-related capabilities.
- Correlate kernel crash artifacts with subsequent process privilege changes to surface exploitation attempts.
Monitoring Recommendations
- Forward kernel and Bluetooth subsystem logs to a centralized analytics platform for retention and correlation.
- Alert on repeated Bluetooth driver faults from the same device or user session.
- Track patch deployment status against the MediaTek July 2025 bulletin to measure remediation coverage.
How to Mitigate CVE-2025-20680
Immediate Actions Required
- Apply OEM firmware updates that incorporate MediaTek Patch ID WCNCR00418044 as soon as they are released for your device platform.
- Identify all devices running affected chipsets (MT7902, MT7920, MT7921, MT7922, MT7925, MT7927) or the NB-IoT SDK and prioritize them for remediation.
- Restrict local code execution on affected devices through application allowlisting and least-privilege user accounts.
Patch Information
MediaTek addressed the vulnerability in the July 2025 Product Security Bulletin under Patch ID WCNCR00418044 and Issue ID MSV-3482. Patches must be integrated and distributed by downstream OEMs and platform vendors. Consult the MediaTek Product Security Bulletin - July 2025 for the authoritative list of patched components and integration guidance.
Workarounds
- Disable Bluetooth on affected devices when the functionality is not required, particularly in high-risk environments.
- Limit installation of untrusted applications that could deliver the local attacker payload required for exploitation.
- Enforce device management policies that block sideloading and restrict access to Bluetooth driver interfaces until firmware is updated.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
