CVE-2026-20446 Overview
CVE-2026-20446 is a memory corruption vulnerability affecting MediaTek's secure boot component. The flaw stems from an integer overflow condition that can lead to an out-of-bounds write operation. An attacker with physical access to a vulnerable device can exploit this vulnerability to cause a local denial of service condition. The vulnerability requires User execution privileges but does not require user interaction for exploitation.
Critical Impact
Physical attackers with user-level privileges can exploit this integer overflow in MediaTek's secure boot component to trigger an out-of-bounds write, resulting in denial of service and potential device unavailability.
Affected Products
- MediaTek MT6813 Firmware
- MediaTek MT6813 Hardware
- Devices utilizing MediaTek MT6813 chipset with affected firmware
Discovery Timeline
- 2026-04-07 - CVE-2026-20446 published to NVD
- 2026-04-07 - Last updated in NVD database
Technical Details for CVE-2026-20446
Vulnerability Analysis
This vulnerability affects the secure boot (sec boot) component of MediaTek MT6813 chipsets. The root cause is an integer overflow condition (CWE-190) that subsequently enables an out-of-bounds write operation (CWE-787). During the secure boot process, improper handling of arithmetic operations can cause integer values to wrap around, resulting in a smaller-than-expected buffer allocation or incorrect boundary calculations. This allows data to be written beyond the intended memory boundaries.
The physical attack vector requirement indicates that exploitation necessitates direct hardware access to the target device, significantly limiting the attack surface compared to remote vulnerabilities. However, in scenarios where an attacker can gain physical access—such as stolen devices, supply chain attacks, or targeted physical intrusion—this vulnerability could be leveraged to disrupt device operation.
Root Cause
The vulnerability originates from insufficient validation of arithmetic operations within the secure boot component. When certain values are processed during the boot sequence, an integer overflow can occur, causing the resulting value to wrap around to a much smaller number than intended. This leads to allocation of an undersized buffer or miscalculation of memory boundaries. Subsequent write operations then exceed the allocated memory region, corrupting adjacent memory and causing system instability or crashes.
The combination of CWE-190 (Integer Overflow or Wraparound) and CWE-787 (Out-of-bounds Write) represents a common pattern where arithmetic errors cascade into memory safety violations.
Attack Vector
The attack requires physical access to a device equipped with the MediaTek MT6813 chipset. An attacker would need to:
- Gain physical access to the target device
- Execute code with User-level privileges
- Trigger the vulnerable code path within the secure boot component
- Cause the integer overflow condition that leads to the out-of-bounds write
The exploitation does not require user interaction, meaning that once the attacker has physical access and appropriate privileges, the vulnerability can be triggered programmatically. The resulting denial of service could render the device unusable until recovery actions are taken.
The vulnerability mechanism involves arithmetic operations in the secure boot component where large input values cause integer overflow. When the overflowed value is used for memory allocation or boundary checks, it results in undersized buffers or incorrect boundary calculations, allowing subsequent write operations to corrupt memory beyond the intended region. For detailed technical specifications, refer to the MediaTek Security Bulletin April 2026.
Detection Methods for CVE-2026-20446
Indicators of Compromise
- Unexpected device crashes or reboots during boot sequence
- Abnormal secure boot failure messages or error codes in device logs
- Evidence of physical tampering or unauthorized device access
- Memory corruption indicators in system diagnostic logs
Detection Strategies
- Monitor device boot logs for anomalous secure boot behavior or error patterns
- Implement firmware integrity verification to detect unauthorized modifications
- Deploy physical security controls and tamper-evident mechanisms for sensitive devices
- Utilize SentinelOne Singularity platform for endpoint monitoring and anomaly detection
Monitoring Recommendations
- Enable verbose logging for secure boot components where supported by device firmware
- Establish baseline boot behavior metrics to identify deviations indicative of exploitation attempts
- Implement centralized log aggregation for devices in high-risk physical environments
- Configure alerts for repeated boot failures or secure boot error conditions
How to Mitigate CVE-2026-20446
Immediate Actions Required
- Apply the security patch identified by Patch ID: ALPS09963054 from MediaTek
- Review and strengthen physical security controls for devices containing MT6813 chipsets
- Restrict user-level execution privileges on sensitive devices where feasible
- Conduct inventory assessment to identify all affected devices in your environment
Patch Information
MediaTek has released a security patch addressing this vulnerability. The patch is tracked under Patch ID: ALPS09963054 and Issue ID: MSV-3899. Organizations should obtain the updated firmware through their device manufacturer or MediaTek's official distribution channels. Refer to the MediaTek Security Bulletin April 2026 for detailed patch information and availability timelines specific to your device vendor.
Device manufacturers integrating MediaTek chipsets should coordinate with MediaTek to incorporate this patch into their firmware update cycles. End users should apply firmware updates from their device manufacturer as they become available.
Workarounds
- Implement strict physical access controls to limit unauthorized device access
- Utilize device encryption and secure storage to protect against data extraction in case of physical compromise
- Consider device retirement or isolation for high-value assets until patches are applied
- Enable any available secure boot integrity verification features supported by the device
# Configuration example - Physical security and access control recommendations
# Ensure devices are stored in secure, access-controlled environments
# Implement tamper-evident seals on device enclosures
# Maintain device access logs for audit purposes
# Verify firmware version to confirm patch application status
# Check device settings for secure boot integrity verification options
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
