CVE-2026-20490: CCCI Out of Bounds Read DoS Vulnerability

CVE-2026-20490 Overview

CVE-2026-20490 is an out-of-bounds read vulnerability in the MediaTek ccci (Cross Core Communication Interface) component. The flaw stems from a missing bounds check that allows a local attacker with existing System-level privileges to trigger a denial of service condition. No user interaction is required for exploitation. MediaTek tracks the fix under Patch ID ALPS10981501 and Issue ID MSV-7669, published in the MediaTek Product Security Bulletin for August 2026.

Critical Impact
A local attacker with System privileges can trigger an out-of-bounds read in the ccci component, resulting in denial of service on affected MediaTek-powered devices.

Affected Products

MediaTek chipsets exposing the ccci (Cross Core Communication Interface) component
Android devices built on affected MediaTek platforms
Refer to the MediaTek Security Bulletin August 2026 for the specific chipset list

Discovery Timeline

2026-08-03 - CVE-2026-20490 published to NVD
2026-08-03 - Last updated in NVD database
MediaTek releases patch ALPS10981501 in the MediaTek Security Bulletin August 2026

Technical Details for CVE-2026-20490

Vulnerability Analysis

The vulnerability resides in the MediaTek ccci driver, which handles communication between the application processor and the modem processor on MediaTek platforms. The driver processes input data without validating buffer boundaries before performing a read operation. This missing bounds check is classified as [CWE-125] Out-of-bounds Read.

When an attacker with System privileges supplies crafted input to the affected code path, the driver reads memory outside the intended buffer. The read triggers abnormal kernel behavior, causing the affected process or the device to become unresponsive. The impact is limited to availability, with no confidentiality or integrity effects.

Root Cause

The ccci component fails to enforce a bounds check on an index or length value used during a read operation. The absence of validation allows the driver to dereference memory beyond the allocated region. Vendors commonly introduce this class of defect when trusted boundaries between privileged callers and kernel drivers are assumed rather than enforced.

Attack Vector

Exploitation requires local access and pre-existing System privileges on the target device. The attacker interacts with the ccci interface from a compromised System-level process or application. No user interaction is required. Because System privilege is a prerequisite, the vulnerability is most relevant as a post-compromise capability that enables an attacker to destabilize the device or chain with other issues.

No verified public proof-of-concept code is available. For technical details, refer to the MediaTek Security Bulletin August 2026.

Detection Methods for CVE-2026-20490

Indicators of Compromise

Unexpected kernel crashes or tombstone files referencing the ccci driver in /data/tombstones/
Repeated modem or baseband subsystem restarts recorded in logcat and dmesg
Device reboots or freezes correlated with System-privileged process activity

Detection Strategies

Monitor Android device logs for kernel oops or panic events referencing ccci symbols
Inspect installed applications and system components granted System UID for unauthorized code
Track MediaTek patch level reported by devices against the August 2026 security bulletin

Monitoring Recommendations

Aggregate mobile device kernel logs and crash reports in a centralized telemetry pipeline
Alert on abnormal frequency of baseband or ccci driver faults across managed device fleets
Correlate device instability with recent application installations or privilege escalation events

How to Mitigate CVE-2026-20490

Immediate Actions Required

Apply the MediaTek security patch level referenced in the August 2026 bulletin as soon as the device OEM makes it available
Restrict installation of applications requesting System-level privileges to trusted sources only
Enforce mobile device management (MDM) policies that require current security patch levels for network access

Patch Information

MediaTek published the fix under Patch ID ALPS10981501 (Issue ID MSV-7669). The patch is distributed to device OEMs, which integrate it into their Android security updates. Consult the MediaTek Security Bulletin August 2026 and the corresponding OEM security bulletin for device-specific update availability.

Workarounds

No vendor-supplied workaround exists; installing the patched Android security update is the only remediation
Reduce risk by removing unnecessary applications and services that hold or request System privileges
Monitor device fleets for signs of privilege escalation that would satisfy the exploitation prerequisite