CVE-2025-20747 is a stack overflow vulnerability classified under CWE-121, found in the GNSS (Global Navigation Satellite System) service component of multiple MediaTek chipsets including MT2718, MT2737, MT6835, MT6878, MT6886, MT6897, MT6899, MT6982, MT6985, MT6986, MT6986D, MT6989, MT6990, MT6991, MT8676, MT8678, MT8755, and MT8893. The root cause is an incorrect bounds check that allows an out-of-bounds write on the stack, which can corrupt memory and lead to privilege escalation. This vulnerability requires the attacker to already possess System-level privileges on the device, meaning it is not exploitable remotely or by unprivileged users. No user interaction is needed, so exploitation can be automated once System access is obtained. Affected platforms include Android versions 14.0 and 15.0, as well as embedded Linux distributions such as openWRT (21.02 and 23.05), Yocto 4.0, RDK-B 24Q1, and Zephyr 3.7.0, indicating a broad range of devices from smartphones to IoT and embedded systems. The CVSS v3.1 base score is 6.7, reflecting a medium severity with high impact on confidentiality, integrity, and availability but limited attack vector (local) and requiring high privileges. The vulnerability was published on November 4, 2025, with no known exploits in the wild at this time. A patch identified as ALPS10010443 exists but no direct links are provided. The vulnerability's exploitation could allow attackers to escalate privileges locally, potentially leading to full system compromise or persistent control over affected devices. This is particularly concerning for devices in critical infrastructure or enterprise environments where MediaTek chipsets are deployed. The vulnerability highlights the importance of secure coding practices around bounds checking in embedded system services.

For European organizations, this vulnerability poses a significant risk primarily in environments where MediaTek chipsets are deployed in devices running Android 14/15 or embedded Linux variants. The potential impact includes local privilege escalation, which could lead to unauthorized access to sensitive data, disruption of device functionality, or persistent compromise. This is especially critical for sectors relying on IoT devices, telecommunications infrastructure, or embedded systems in industrial control, smart city deployments, or automotive applications. Confidentiality, integrity, and availability of systems could be severely affected if exploited. Although exploitation requires prior System-level access, the vulnerability lowers the barrier for attackers to gain full control once inside, increasing the risk of lateral movement and deeper network compromise. The absence of required user interaction facilitates automated exploitation by malicious insiders or malware with elevated privileges. The medium CVSS score reflects the balance between high impact and limited attack vector, but the real-world impact could be amplified in critical environments. European organizations with large deployments of MediaTek-based devices should consider this a priority vulnerability to address to prevent escalation chains in targeted attacks.

1. Apply the official patch ALPS10010443 from MediaTek or device vendors as soon as it becomes available to close the bounds check flaw. 2. Restrict System-level access on devices using these chipsets to trusted administrators only, employing strong authentication and access controls. 3. Implement runtime protections such as stack canaries, address space layout randomization (ASLR), and control flow integrity (CFI) where supported to mitigate exploitation of stack overflows. 4. Monitor device logs and system behavior for signs of privilege escalation attempts or anomalous GNSS service activity. 5. For embedded Linux devices, ensure secure boot and firmware integrity checks to prevent unauthorized code execution. 6. Conduct regular vulnerability assessments and penetration testing focusing on local privilege escalation vectors. 7. Segment networks to limit lateral movement from compromised devices with System access. 8. Educate administrators about the risks of local privilege escalation vulnerabilities and the importance of timely patching. 9. For IoT deployments, consider device lifecycle management policies that include vulnerability management and patch deployment. 10. Collaborate with vendors to receive timely security updates and advisories related to MediaTek chipsets.