CVE-2025-20747 is a stack overflow vulnerability classified under CWE-121, found in the GNSS (Global Navigation Satellite System) service 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 allows an out-of-bounds write on the stack, which can corrupt memory and lead to privilege escalation. Exploitation requires the attacker to already have System-level privileges on the device, meaning the attacker must have significant access beforehand. No user interaction is necessary, facilitating automated or stealthy exploitation once the attacker has system access. The vulnerability affects devices running Android 14 and 15, 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 wide range of IoT, mobile, and embedded devices are impacted. The vulnerability was published on November 4, 2025, with a CVSS v3.1 score of 6.7 (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H), reflecting a medium severity with high impact on confidentiality, integrity, and availability but limited by the requirement for local high privileges. No known exploits have been reported in the wild, and a patch has been identified (ALPS10010443), though no direct patch links are provided. This vulnerability poses a risk primarily in environments where attackers can gain system-level access and then leverage this flaw to further escalate privileges, potentially compromising device security and sensitive data.

The primary impact of CVE-2025-20747 is local privilege escalation on affected devices, which can lead to full system compromise. Since the vulnerability allows an out-of-bounds write on the stack, it can be exploited to execute arbitrary code with elevated privileges, undermining confidentiality, integrity, and availability of the system. This can result in unauthorized access to sensitive information, modification or deletion of critical data, and disruption of device functionality. The affected platforms include a wide range of MediaTek chipsets used in smartphones, IoT devices, routers, and embedded systems, meaning the scope of impact spans consumer, industrial, and enterprise environments. Organizations relying on these devices for critical operations could face operational disruptions, data breaches, and increased risk of persistent threats if attackers chain this vulnerability with initial access exploits. The requirement for existing System privileges limits the attack surface but does not eliminate risk, especially in environments where insider threats or prior compromise is possible. The absence of user interaction lowers the barrier for automated exploitation once system access is obtained.

1. Apply the official patch identified as ALPS10010443 as soon as it becomes available from MediaTek or device manufacturers to remediate the vulnerability. 2. Implement strict access controls and monitoring to prevent unauthorized users from gaining System-level privileges on affected devices. 3. Employ runtime protections such as stack canaries, address space layout randomization (ASLR), and control flow integrity (CFI) where supported to mitigate exploitation of stack overflow vulnerabilities. 4. Regularly update device firmware and operating systems to incorporate security fixes and reduce exposure to known vulnerabilities. 5. Conduct thorough security audits and penetration testing on devices using affected MediaTek chipsets to identify potential privilege escalation paths. 6. Limit the deployment of devices with these chipsets in sensitive environments until patches are confirmed applied. 7. Monitor security advisories from MediaTek and vendors for updates or exploit reports related to this CVE. 8. Employ network segmentation and endpoint detection to quickly identify and isolate compromised devices that may be exploited via this vulnerability.