CVE-2026-20465 Overview
CVE-2026-20465 is an out-of-bounds write vulnerability in the MediaTek WLAN Access Point (AP) driver. The flaw stems from a missing bounds check in the driver code, classified as a heap-based buffer overflow [CWE-122]. An attacker on an adjacent network can trigger the condition without authentication or user interaction. Successful exploitation could lead to escalation of privilege on the affected device. MediaTek tracks the fix under Patch ID WCNCR00489200 and Issue ID MSV-7834.
Critical Impact
An unauthenticated attacker within wireless range can write out-of-bounds memory in the WLAN AP driver, potentially achieving privilege escalation without user interaction.
Affected Products
- MediaTek chipsets containing the affected WLAN AP driver
- Devices referenced in the MediaTek Security Bulletin August 2026
- Downstream OEM firmware integrating the vulnerable driver
Discovery Timeline
- 2026-08-03 - CVE-2026-20465 published to NVD
- 2026-08-05 - Last updated in NVD database
Technical Details for CVE-2026-20465
Vulnerability Analysis
The vulnerability resides in the WLAN AP driver code path that handles incoming wireless frame data. A missing bounds check allows attacker-controlled input to exceed the allocated heap buffer, resulting in an out-of-bounds write. Because the driver operates in a privileged context, memory corruption at this layer can be leveraged to alter kernel-adjacent structures. The condition is reachable over the air from an adjacent network position, requiring no authentication credentials and no user interaction. The EPSS score is 0.203% at the 10.465 percentile at time of publication.
Root Cause
The root cause is an absent length validation before copying attacker-influenced data into a fixed-size heap buffer within the WLAN AP driver. When frame or attribute lengths exceed the destination buffer, the driver writes past the buffer boundary. This class of defect corresponds to CWE-122 (Heap-based Buffer Overflow) and typically arises when parsing routines trust length fields supplied by peer devices.
Attack Vector
Exploitation requires the attacker to be within wireless range of a device running the vulnerable driver in AP mode. The attacker crafts a malformed wireless frame with length fields designed to overflow the target buffer. Because privileges are not required and no user interaction is needed, a nearby attacker can transmit the payload directly. Reliable exploitation depends on shaping the heap layout to convert the write primitive into control over execution or privileged data structures.
No verified proof-of-concept code is available. See the MediaTek Security Bulletin August 2026 for vendor-supplied technical details.
Detection Methods for CVE-2026-20465
Indicators of Compromise
- Unexpected WLAN driver crashes, kernel panics, or watchdog resets on devices operating in AP mode
- Malformed management or data frames from adjacent stations preceding driver instability
- Unusual privileged process activity spawned shortly after wireless anomalies
Detection Strategies
- Monitor kernel logs (dmesg, logcat) for driver faults referencing WLAN AP components
- Inspect wireless captures for oversized information elements or malformed attributes targeting the AP interface
- Correlate wireless anomalies with subsequent privilege changes or unexpected process launches
Monitoring Recommendations
- Enable telemetry from mobile and IoT devices into a centralized data lake for behavioral correlation
- Track firmware and patch levels across the fleet to identify unpatched MediaTek-based devices
- Alert on repeated driver crash signatures that could indicate exploitation attempts
How to Mitigate CVE-2026-20465
Immediate Actions Required
- Apply the MediaTek patch identified as WCNCR00489200 once distributed by the device OEM
- Inventory devices using MediaTek chipsets operating in WLAN AP mode
- Restrict operation of vulnerable devices in untrusted wireless environments until patched
Patch Information
MediaTek addressed the issue under Patch ID WCNCR00489200 (Issue ID MSV-7834). Details are published in the MediaTek Security Bulletin August 2026. OEMs must integrate the vendor patch into device firmware updates before end users receive protection.
Workarounds
- Disable AP or hotspot mode on affected devices where the functionality is not required
- Operate affected devices only within physically controlled wireless environments
- Segment guest and IoT wireless networks to limit adjacent-network attack exposure
# Example: disable Wi-Fi tethering / AP mode on Android via ADB where supported
adb shell settings put global tether_dun_required 0
adb shell svc wifi disable
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
