CVE-2026-20475 Overview
CVE-2026-20475 is an out-of-bounds write vulnerability in the MediaTek display component. The flaw stems from a missing bounds check, allowing a local attacker with System privileges to write outside allocated memory. Successful exploitation can lead to local escalation of privilege without user interaction. MediaTek tracks the fix under Patch ID ALPS11004276 and Issue ID MSV-7748. The weakness is classified under CWE-787 (Out-of-Bounds Write).
Critical Impact
An attacker holding System privileges can escalate further into the device by triggering an out-of-bounds write in the display component, potentially compromising integrity and confidentiality of the affected device.
Affected Products
- MediaTek chipsets containing the vulnerable display component (see MediaTek Product Security Bulletin - August 2026)
- Downstream OEM devices integrating affected MediaTek platforms
- Firmware images predating Patch ID ALPS11004276
Discovery Timeline
- 2026-08-03 - CVE-2026-20475 published to NVD
- 2026-08-05 - Last updated in NVD database
Technical Details for CVE-2026-20475
Vulnerability Analysis
The vulnerability resides in the MediaTek display subsystem, where an input parameter is used to index or size a memory operation without adequate boundary validation. Because the offending write path lacks a bounds check, an attacker can drive the operation past the intended buffer. The result is memory corruption in a privileged context, which can be used to modify kernel or driver state.
Exploitation requires that the attacker already hold the System privilege on the device. From that position, the attacker interacts with the vulnerable display interface to trigger the out-of-bounds write. No user interaction is required to complete the exploitation chain once the prerequisite privilege is obtained.
The impact is limited to the local device, but the outcome is a full privilege escalation beyond System. Confidentiality and integrity impact are high, while availability is unaffected according to the published CVSS vector.
Root Cause
The root cause is a missing bounds check on a value that governs a write operation in the display component. When an attacker-supplied index or length exceeds the size of the target buffer, the write proceeds and corrupts adjacent memory. This is a classic CWE-787 pattern in a kernel-adjacent driver path.
Attack Vector
The attack vector is local. An actor with System privileges invokes the affected display interface with crafted parameters. The vulnerable code path performs the write without validating that the target offset falls within the allocated region. The corruption yields elevated execution primitives that the attacker can chain into further escalation.
No verified public proof-of-concept is available. Technical specifics are limited to the vendor advisory referenced by MediaTek. See the MediaTek Product Security Bulletin for authoritative details.
Detection Methods for CVE-2026-20475
Indicators of Compromise
- Unexpected crashes, panics, or reboots originating from the MediaTek display driver in kernel logs
- Processes running with System privileges issuing unusual ioctl calls to display device nodes
- Post-exploitation artifacts consistent with privilege escalation beyond System on affected devices
Detection Strategies
- Inventory devices by chipset and firmware level, then flag any device whose baseband or vendor image predates Patch ID ALPS11004276
- Monitor mobile endpoint telemetry for anomalous native crashes tied to the display subsystem
- Correlate System-level process activity with abnormal driver interactions to surface local escalation attempts
Monitoring Recommendations
- Ingest OEM security patch level and MediaTek Security Patch Level (SPL) into asset inventory for compliance tracking
- Alert when devices attach to enterprise services while running firmware below the August 2026 MediaTek SPL
- Retain kernel and driver crash telemetry from mobile fleets for retrospective analysis
How to Mitigate CVE-2026-20475
Immediate Actions Required
- Apply the OEM firmware update that incorporates MediaTek Patch ID ALPS11004276 as soon as it is available for the device model
- Verify that mobile devices report a security patch level of August 2026 or later before granting access to sensitive enterprise resources
- Restrict installation of untrusted applications and sideloaded packages that could seed the prerequisite System-level foothold
Patch Information
MediaTek published the fix in the August 2026 Product Security Bulletin under Patch ID ALPS11004276 (Issue ID MSV-7748). Distribution occurs through downstream OEM firmware updates. Refer to the MediaTek Product Security Bulletin - August 2026 for the authoritative patch reference.
Workarounds
- No vendor-supplied workaround is documented; patch adoption is the supported remediation path
- Enforce mobile device management policies that block enrollment of devices running firmware older than the August 2026 MediaTek SPL
- Reduce attack surface by removing unnecessary privileged applications that could be abused to obtain the System privilege prerequisite
# Verify Android security patch level on a managed device
adb shell getprop ro.build.version.security_patch
# Confirm the device build fingerprint matches an image containing ALPS11004276
adb shell getprop ro.build.fingerprint
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
