CVE-2025-20746 is a stack overflow vulnerability classified under CWE-121, found in the GNSS (Global Navigation Satellite System) service component of numerous 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 leads to an out-of-bounds write operation on the stack. This flaw can be exploited locally by an attacker who already possesses System-level privileges on the device, enabling escalation to higher privileges or potentially compromising system integrity and availability. The vulnerability does not require user interaction, making it easier to exploit once initial access is gained. Affected platforms include Android 14 and 15, openWRT 21.02 and 23.05, Yocto 4.0, RDK-B 24Q1, and Zephyr 3.7.0, indicating a broad impact across embedded and mobile operating systems. The CVSS v3.1 base score is 6.7 (medium severity), reflecting the requirement for high privileges but significant impact on confidentiality, integrity, and availability. No public exploits have been reported yet, but the vulnerability's nature demands timely patching. The issue was reserved in November 2024 and published in November 2025, with patches identified under MediaTek's internal tracking (ALPS10010441, MSV-3967).

For European organizations, the impact of CVE-2025-20746 can be substantial, especially for sectors relying on embedded systems and IoT devices powered by MediaTek chipsets. Telecommunications providers, smart city infrastructure, industrial automation, and consumer electronics manufacturers could experience risks including unauthorized privilege escalation, leading to potential data breaches, service disruption, or device manipulation. Since the vulnerability affects GNSS services, critical systems relying on accurate location and timing data could be compromised, affecting logistics, transportation, and emergency services. The requirement of existing System privileges limits remote exploitation but insider threats or chained attacks exploiting other vulnerabilities could leverage this flaw to gain full control. The broad range of affected operating systems used in embedded environments increases the attack surface. Failure to patch could result in increased risk of espionage, sabotage, or operational downtime, impacting compliance with European cybersecurity regulations such as NIS2 and GDPR where applicable.

1. Apply official patches from MediaTek and device manufacturers immediately once available to remediate the out-of-bounds write vulnerability. 2. Restrict and monitor access to System-level privileges on devices using affected chipsets to prevent unauthorized local exploitation. 3. Implement strict access controls and endpoint protection to detect and prevent privilege escalation attempts. 4. Conduct thorough security audits of embedded devices and IoT infrastructure to identify the presence of affected MediaTek chipsets and vulnerable OS versions. 5. Employ network segmentation to isolate critical GNSS-dependent systems, reducing the impact of a compromised device. 6. Monitor logs and system behavior for anomalies indicative of exploitation attempts, especially in environments with high-value targets. 7. Coordinate with vendors for firmware updates and validate patch deployment across all affected devices. 8. Educate internal teams on the risks of local privilege escalation vulnerabilities and the importance of layered security controls. 9. Consider implementing runtime protections such as stack canaries and address space layout randomization (ASLR) where supported to mitigate exploitation.