CVE-2025-20697 is a vulnerability classified under CWE-787 (Out-of-bounds Write) affecting multiple MediaTek SoCs including MT2718, MT6761, MT6765, MT6768, MT6853, MT6855, MT6877, MT6878, MT6879, MT6883, MT6885, MT6889, MT6893, MT6897, MT6989, MT6991, MT8186, MT8196, MT8391, MT8678, MT8775, MT8786, MT8788E, MT8792, MT8796, MT8873, MT8883, and MT8893. These chipsets are integrated in devices running Android 14 and 15. The vulnerability exists in the Power Hardware Abstraction Layer (HAL) due to a missing bounds check, which allows an out-of-bounds write operation. This flaw can be exploited locally by an attacker who already has System privileges, enabling escalation to higher privileges or potentially full control over the device. The exploit does not require user interaction, increasing the risk if System-level access is compromised through other vulnerabilities or insider threats. The vulnerability impacts confidentiality, integrity, and availability, as arbitrary memory writes can lead to code execution or system crashes. The CVSS v3.1 score of 6.7 reflects a medium severity with attack vector local, low attack complexity, high privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. While no public exploits are known, the vulnerability demands attention due to the widespread use of affected MediaTek chipsets in consumer and enterprise Android devices. The patch has been identified (ALPS09915681), but deployment status is unclear.

The vulnerability allows local attackers with System privileges to perform out-of-bounds writes, potentially leading to privilege escalation and full system compromise. This can result in unauthorized access to sensitive data, modification or corruption of system files, and denial of service through system instability or crashes. Given the affected chipsets are widely used in smartphones and IoT devices, the impact spans consumer privacy breaches, disruption of critical communications, and potential footholds for advanced persistent threats. Organizations relying on devices with these MediaTek chipsets may face increased risks of insider threats or chained exploits where an attacker leverages this vulnerability after gaining initial System access. The absence of required user interaction facilitates stealthy exploitation. Although exploitation requires high privileges, the consequences of successful exploitation are severe, affecting confidentiality, integrity, and availability of the device and potentially the broader network it connects to.

1. Apply the official patch ALPS09915681 as soon as it becomes available from device manufacturers or MediaTek to address the missing bounds check in the Power HAL. 2. Enforce strict privilege separation and minimize the number of processes or users with System-level privileges to reduce the attack surface. 3. Implement runtime protections such as memory safety checks, bounds checking, and control flow integrity where possible to detect or prevent out-of-bounds writes. 4. Monitor devices for unusual behavior indicative of privilege escalation attempts or memory corruption. 5. Employ layered security controls including application sandboxing and mandatory access controls (e.g., SELinux) to limit the impact of compromised System-level processes. 6. Conduct regular security audits and penetration testing focusing on privilege escalation vectors within devices using these MediaTek chipsets. 7. Educate users and administrators about the risks of granting or escalating privileges unnecessarily. 8. Coordinate with device vendors to ensure timely firmware and OS updates are deployed across all affected devices in the environment.