CVE-2025-20721 is a vulnerability classified under CWE-787 (Out-of-bounds Write) discovered in the imgsensor component of multiple MediaTek chipsets including MT6886, MT6897, MT6899, MT6985, MT6989, MT6991, MT8195, MT8196, MT8370, MT8390, MT8395, MT8792, and MT8793. The root cause is a missing bounds check in the imgsensor code, which allows an attacker with existing System-level privileges to perform an out-of-bounds write. This memory corruption can lead to local privilege escalation, potentially granting higher privileges or control over the device. The vulnerability affects devices running IoT-v25.0 and Android versions 13.0 through 16.0, which are common in modern smartphones and IoT devices using these chipsets. Exploitation does not require user interaction, increasing the risk of automated or stealthy attacks. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and requiring only limited privileges. No public exploits have been reported yet, but the vulnerability is publicly disclosed and patches are referenced by MediaTek under patch ID ALPS10089545. The flaw could be leveraged by malicious actors who have already compromised the system to gain further control or persistence, making it a critical component in multi-stage attacks.

The vulnerability enables local privilege escalation on devices using affected MediaTek chipsets, potentially allowing attackers to gain root or kernel-level access from System privileges. This can lead to full device compromise, unauthorized access to sensitive data, installation of persistent malware, or disruption of device functionality. Given the widespread use of these chipsets in smartphones and IoT devices, the impact spans consumer privacy breaches, enterprise data leaks, and disruption of critical IoT infrastructure. Attackers could use this flaw to bypass security controls, escalate privileges after initial compromise, or maintain stealthy persistence. The lack of user interaction requirement increases the risk of automated exploitation in targeted or opportunistic attacks. Although no exploits are currently known in the wild, the vulnerability's characteristics make it a significant threat to device security and user trust worldwide.

Organizations and users should immediately apply the official patches provided by MediaTek (Patch ID: ALPS10089545) once available. Until patches are deployed, restrict local access to devices to trusted personnel only, as exploitation requires System-level privileges. Employ robust endpoint protection and monitoring to detect suspicious local activity indicative of privilege escalation attempts. Implement strict application whitelisting and sandboxing to limit the ability of compromised processes to escalate privileges. Regularly update device firmware and operating systems to incorporate security fixes. For IoT deployments, segment networks to isolate vulnerable devices and reduce attack surface. Security teams should conduct thorough audits of devices using affected chipsets to identify potential compromises and ensure compliance with patch management policies. Additionally, vendors should consider adding runtime bounds checking and memory safety mechanisms in future firmware updates to prevent similar issues.