CVE-2025-20774 Overview
CVE-2025-20774 is an out-of-bounds write vulnerability in the MediaTek display component shipped with Google Android devices. The flaw stems from a missing bounds check that allows a process holding System privileges to write outside an allocated buffer. Successful exploitation leads to local escalation of privilege without any user interaction. MediaTek tracks the issue as MSV-4796 and addressed it under Patch ID ALPS10196993. The flaw affects a broad set of MediaTek chipsets used in smartphones, tablets, and automotive platforms, combined with Android 14, 15, and 16.
Critical Impact
A local attacker who has already gained System privileges can trigger an out-of-bounds write in the display driver to escalate to a higher privilege context on the device.
Affected Products
- Google Android 14, 15, and 16
- MediaTek chipsets including MT6739, MT6761, MT6765, MT6768, MT6781, MT6789, MT6833, MT6835, MT6853, MT6855, MT6877, MT6878, MT6879, MT6883, MT6885, MT6886, MT6889, MT6893, MT6895, MT6897, MT6899, MT6983, MT6985, MT6989, and MT6991
- MediaTek automotive and tablet SoCs MT2718, MT8196, MT8676, MT8678, MT8792, and MT8793
Discovery Timeline
- 2025-12-02 - CVE-2025-20774 published to NVD
- 2025-12-03 - Last updated in NVD database
Technical Details for CVE-2025-20774
Vulnerability Analysis
The vulnerability resides in the MediaTek display component used by the Android graphics stack. A code path accepts a length or index value from a privileged caller and uses it to write into a fixed-size buffer without first validating that the value fits within the allocated region. The result is an out-of-bounds write classified under [CWE-787] and [CWE-122], indicating a heap-based memory corruption pattern.
Because the entry point requires System-level privileges, the issue is not directly reachable by ordinary third-party applications. Instead, it functions as a second-stage primitive. An attacker who has already compromised a System process can chain this flaw to corrupt kernel-adjacent display structures and elevate further toward kernel context.
Root Cause
The root cause is the absence of a bounds check before writing to a buffer in the display driver. Input values that should be validated against the destination size are trusted, producing a deterministic linear or indexed write past the buffer boundary.
Attack Vector
Exploitation is local and requires no user interaction. The attacker must first hold System privileges on the device, typically obtained through a separate vulnerability or a malicious privileged service. Once that prerequisite is met, the attacker issues crafted requests to the display interface that drive the unchecked write, corrupting adjacent heap metadata or function pointers to gain higher privilege.
No public proof-of-concept code is available, and detailed exploitation specifics are described in prose only. See the MediaTek Security Bulletin December 2025 for vendor-supplied technical context.
Detection Methods for CVE-2025-20774
Indicators of Compromise
- Unexpected crashes or tombstone files in /data/tombstones referencing the MediaTek display driver or SurfaceFlinger.
- Kernel log entries showing memory corruption, slab corruption, or KASAN reports near display-related symbols.
- System processes with display driver handles spawning unexpected child processes or loading unsigned libraries.
Detection Strategies
- Monitor Android devices for repeated System-level process crashes that map back to the MediaTek display HAL.
- Correlate privileged process exploitation attempts with subsequent privilege escalation behaviors such as SELinux denials transitioning between domains.
- Track installation of applications requesting privileged platform signatures or signed by non-OEM certificates.
Monitoring Recommendations
- Ingest Android logcat, dmesg, and dropbox artifacts into a centralized logging platform for anomaly detection.
- Alert on devices missing the December 2025 MediaTek security patch level after the next monthly rollout.
- Review mobile device management (MDM) inventory for chipset and Android version combinations matching the affected list.
How to Mitigate CVE-2025-20774
Immediate Actions Required
- Apply the December 2025 Android security patch level to all MediaTek-based devices in your fleet.
- Enforce MDM policies that block enrollment of devices running below the December 2025 patch level.
- Restrict installation of applications carrying platform or System signatures to vendor-approved sources only.
Patch Information
MediaTek released the fix under Patch ID ALPS10196993, tracked internally as Issue ID MSV-4796. OEMs distribute the patch through the Android December 2025 monthly security update. Refer to the MediaTek Security Bulletin December 2025 for the complete list of patched chipsets and integration guidance for device manufacturers.
Workarounds
- No vendor-supplied workaround exists. Apply the official patch as soon as the OEM makes it available.
- Reduce risk of the prerequisite System compromise by removing unnecessary privileged applications and disabling sideloading on managed devices.
- Enable Google Play Protect and OEM-provided integrity services to identify malicious privileged software that could chain into this flaw.
# Verify Android security patch level on a managed device
adb shell getprop ro.build.version.security_patch
# Expected output for remediated devices: 2025-12-01 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
