CVE-2025-20763: Google Android Privilege Escalation Flaw

CVE-2025-20763 Overview

CVE-2025-20763 is a high-severity out-of-bounds write vulnerability discovered in the MediaTek mmdvfs (Multimedia Dynamic Voltage and Frequency Scaling) component affecting numerous MediaTek chipsets used in Android devices. The vulnerability exists due to a missing bounds check, which could allow an attacker who has already obtained System privilege to achieve local escalation of privilege. No user interaction is required for exploitation.

This vulnerability is classified as CWE-787 (Out-of-Bounds Write) and affects devices running Android 14.0, 15.0, and 16.0 with vulnerable MediaTek chipsets. The flaw has been assigned a CVSS 3.1 score of 7.8 (HIGH) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating high impact on confidentiality, integrity, and availability.

Critical Impact

Local privilege escalation vulnerability in MediaTek mmdvfs component enables attackers with System privilege to further escalate privileges without user interaction, potentially leading to complete device compromise.

Affected Products

• Google Android 14.0, 15.0, 16.0
• MediaTek MT6833, MT6835, MT6853, MT6855, MT6877, MT6878, MT6879
• MediaTek MT6883, MT6885, MT6886, MT6889, MT6893, MT6895, MT6897
• MediaTek MT6899, MT6983, MT6985, MT6989, MT6991
• MediaTek MT8196, MT8676, MT8678, MT8792, MT8793, MT8796, MT8873, MT8893

Discovery Timeline

• December 2, 2025 - CVE-2025-20763 published to NVD
• December 3, 2025 - Last updated in NVD database

Technical Details for CVE-2025-20763

Vulnerability Analysis

The vulnerability resides in the mmdvfs component, which is responsible for managing multimedia dynamic voltage and frequency scaling on MediaTek chipsets. The mmdvfs subsystem dynamically adjusts voltage and frequency parameters to optimize power consumption and performance for multimedia workloads such as video playback, camera operations, and display rendering.

The flaw stems from a missing bounds check in the mmdvfs driver code. When processing certain input parameters or data structures, the component fails to properly validate array indices or buffer sizes before performing write operations. This allows an attacker to write data beyond the allocated buffer boundaries, potentially corrupting adjacent memory regions.

With a CVSS vector of CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, the vulnerability requires local access with low privileges and has low attack complexity. The impact affects all three security properties at a high level, making this a significant threat for affected devices.

The EPSS (Exploit Prediction Scoring System) indicates a probability of 0.005% with a percentile of 21.1%, suggesting relatively low predicted exploitation activity at this time.

Root Cause

The root cause of CVE-2025-20763 is the absence of proper bounds checking before memory write operations in the mmdvfs driver. When handling input data related to voltage and frequency scaling configurations, the code does not validate that indices or sizes fall within expected ranges. This classic programming error allows write operations to proceed with out-of-bounds memory addresses.

The missing validation occurs in the kernel-level driver code, which processes requests from userspace or other kernel components. Without proper boundary validation, malformed or malicious input can direct the driver to write to memory locations outside the intended buffer, leading to memory corruption.

Attack Vector

The attack vector for CVE-2025-20763 is local, requiring an attacker to first obtain System-level privileges on the target device. Once System privilege is achieved (potentially through another exploit or vulnerability chain), the attacker can interact with the vulnerable mmdvfs component to trigger the out-of-bounds write condition.

The exploitation process involves crafting specific input that causes the mmdvfs driver to write beyond buffer boundaries. By carefully controlling the write offset and data, an attacker could:

1. Corrupt kernel memory structures to gain additional privileges
2. Overwrite function pointers to redirect execution flow
3. Modify security-critical data structures in kernel memory
4. Achieve arbitrary code execution in kernel context

Since no user interaction is required once System privilege is obtained, this vulnerability can be exploited silently as part of a privilege escalation chain.

Detection Methods for CVE-2025-20763

Indicators of Compromise

• Unexpected system crashes or kernel panics related to mmdvfs or multimedia subsystems
• Anomalous memory access patterns in kernel logs involving the mmdvfs driver
• Privilege escalation attempts detected after initial System-level compromise
• Suspicious ioctl calls or interactions with /dev/ nodes associated with mmdvfs

Detection Strategies

Organizations can implement the following detection strategies to identify potential exploitation attempts:

Kernel Log Monitoring: Monitor for kernel log entries related to mmdvfs driver errors, memory access violations, or out-of-bounds access warnings. Look for patterns indicating buffer overflows or memory corruption in multimedia-related subsystems.

System Call Monitoring: Implement monitoring for unusual system calls or ioctl operations targeting mmdvfs-related device nodes. Baseline normal behavior and alert on anomalous patterns.

Behavioral Analysis: Deploy endpoint detection solutions capable of identifying privilege escalation attempts and unusual process behavior following initial compromise at System level.

Memory Integrity Checks: Utilize kernel security features and memory protection mechanisms to detect unauthorized modifications to kernel memory regions.

Monitoring Recommendations

Security teams should implement comprehensive monitoring across their Android device fleet:

1. Enable detailed kernel logging on affected devices during security assessments
2. Deploy Mobile Threat Defense (MTD) solutions with kernel-level monitoring capabilities
3. Implement centralized log aggregation for fleet-wide visibility
4. Configure alerts for security-relevant events from MediaTek driver components
5. Conduct regular vulnerability scanning to identify unpatched devices

SentinelOne Singularity Mobile provides advanced threat detection capabilities for Android devices, including behavioral analysis that can identify privilege escalation attempts and anomalous driver interactions that may indicate exploitation of vulnerabilities like CVE-2025-20763.

How to Mitigate CVE-2025-20763

Immediate Actions Required

• Apply security patches as referenced in Patch ID ALPS10267218 from MediaTek
• Update affected Android devices to the latest available firmware version
• Restrict access to devices where patches cannot be immediately applied
• Monitor affected devices for signs of compromise or exploitation attempts
• Implement additional access controls to limit exposure of vulnerable devices

Patch Information

MediaTek has released a security patch to address this vulnerability. The patch is tracked as:

• Patch ID: ALPS10267218
• Issue ID: MSV-5032

The patch adds proper bounds checking to the mmdvfs driver to prevent out-of-bounds write operations. Organizations should obtain the patch through their device manufacturers or Android OEM partners, as MediaTek provides patches to device vendors who then integrate them into their firmware updates.

For detailed patch information, refer to the MediaTek Product Security Bulletin for December 2025.

Device manufacturers using affected MediaTek chipsets should:

1. Integrate the ALPS10267218 patch into their Android builds
2. Release firmware updates to end users
3. Communicate the availability of security updates to customers

Workarounds

In environments where immediate patching is not possible, consider the following risk mitigation measures:

Restrict Physical Access: Since this is a local vulnerability requiring System-level privileges, limiting physical access to devices reduces the attack surface.

Device Management Policies: Implement strict device management policies to prevent installation of untrusted applications that could be used to gain initial System-level access.

Network Segmentation: Isolate unpatched devices from sensitive network resources until patches can be applied.

Security Monitoring: Enhance monitoring on affected devices to detect any suspicious activity that could indicate exploitation attempts.

# Android device security configuration recommendations
# Verify device security patch level
adb shell getprop ro.build.version.security_patch

# Check for MediaTek chipset model
adb shell cat /proc/cpuinfo | grep Hardware

# Monitor kernel logs for mmdvfs-related anomalies
adb shell dmesg | grep -i mmdvfs