What is the CVSS score of CVE-2025-20711?

CVE-2025-20711 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.3%.

How to fix or mitigate CVE-2025-20711?

Within 24 hours, inventory all access points running MediaTek WLAN AP drivers, especially MediaTek SDK-based firmware and OpenWrt 19.07.0/21.02.0 images built for MediaTek Wi-Fi chipsets, confirm AP mode operation, and isolate or disable AP mode on non-essential devices while restricting wireless coverage where feasible. Within 7 days, engage MediaTek or the OEM to obtain and validate the vendor fix referenced as Patch ID WCNCR00422399 (issue MSV-3748), because no vendor-released patch version is identified in the provided data, and apply it to affected APs after testing. Within 30 days, replace or upgrade end-of-support OpenWrt 19.07.0/21.02.0 MediaTek Wi-Fi deployments to supported firmware, segment AP management traffic, and monitor wireless infrastructure for memory-corruption or crash indicators; if patch deployment is not possible, maintain compensating controls such as disabling AP mode, reducing radio range, and enforcing network segmentation.

MediaTek WLAN Driver CVE-2025-20711

HIGH

Out-of-bounds Write (CWE-787)

2025-10-14 security@mediatek.com

Privilege Escalation Buffer Overflow Memory Corruption Mediatek Openwrt Software Development Kit

8.8

CVSS 3.1 · Vendor: mediatek

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Position within Wi-Fi radio range
Delivery

Send crafted 802.11 frame to AP
Exploit

Trigger out-of-bounds write in driver
Execution

Corrupt kernel memory state
Impact

Escalate to elevated privileges

Vulnerability Assessment

Weakness	CWE CWE-787 ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, write limits MITRE ATT&CK 2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	The target device must be running the affected MediaTek WLAN access-point (AP) driver in AP mode (e.g., MediaTek SDK-based firmware, including OpenWrt 19.07.0/21.02.0 builds on MediaTek Wi-Fi). Exploitation requires no authentication and no user interaction (PR:N/UI:N), but is limited to an attacker within wireless radio range (AV:A, 'proximal/adjacent') - it cannot be performed across the internet. The practical limiting factors are therefore physical proximity to the radio and the presence of the vulnerable AP-mode driver; devices not operating as an AP or already patched (Patch ID WCNCR00422399) are not exposed.
Impact	Signals are mixed, pointing to a technically serious but not yet broadly exploited flaw. The CVSS 3.1 vector (AV:A/AC:L/PR:N/UI:N, C:H/I:H/A:H, base 8.8) is strong: no authentication, no user interaction, low complexity, and full compromise - but the Adjacent (AV:A) attack vector means the attacker must be within wireless radio range, which materially constrains remote mass exploitation compared to a true network (AV:N) bug. This is consistent with the description's 'remote (proximal/adjacent)' wording, so the vector and description agree. Against that, EPSS is low (0.31%, 22nd percentile), there is no CISA KEV listing and no public exploit identified at time of analysis, indicating no observed or predicted widespread exploitation. No SSVC decision data was provided in the input. Net: this is a credible priority for the specific population of MediaTek WLAN-AP devices (patch promptly), but the proximity requirement plus absence of KEV/POC/high-EPSS argues against emergency network-wide response - it is a high-CVSS flaw whose real-world risk is gated by physical radio-range access and currently has no evidence of active exploitation.
Exploit ScenarioDerived	An attacker within Wi-Fi radio range of a device running the vulnerable MediaTek WLAN access-point driver sends a specially crafted wireless frame that overflows a buffer due to a faulty bounds check, writing out of bounds in driver memory. Because no authentication or user interaction is required, this can corrupt kernel/driver state and escalate privileges on the target. No public exploit identified at time of analysis.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 08, 2026

An out-of-bounds write in the MediaTek WLAN access-point (AP) driver lets an unauthenticated attacker within wireless radio range corrupt memory and escalate privileges on affected access points. Exploitation requires the device to be running the vulnerable driver in AP mode - typically MediaTek SDK-based firmware or OpenWrt 19.07.0/21.02.0 images built for MediaTek Wi-Fi chipsets - and no user interaction or credentials are needed (PR:N/UI:N), though the attacker must be physically proximate (AV:A). The flaw has a public vendor fix (Patch ID WCNCR00422399, issue MSV-3748) and there is no confirmed active exploitation (not in CISA KEV) and no public exploit code identified, with EPSS sitting at a low 0.31% (22nd percentile), so risk is best characterized as technically serious but not yet broadly targeted.

RemediationAI

Patch status: Patch available per vendor advisory - MediaTek has issued Patch ID WCNCR00422399 (tracked as MSV-3748) as documented in the October 2025 MediaTek product security bulletin at https://corp.mediatek.com/product-security-bulletin/October-2025; no standalone patched semantic version number is published in the available data. Primary action is to obtain firmware from the OEM/ODM that integrates that patch and flash it; OpenWrt integrators should rebuild images against a MediaTek driver release that includes WCNCR00422399 and redeploy, noting that shipped 19.07.0 and 21.02.0 trees predate the fix and should in any case be migrated to a currently supported release. If patching cannot be done immediately, the most effective compensating control is to stop running the device in AP mode - the independent assessment indicates non-AP (client/station) operation is not exposed - though this removes the AP's core function and is only viable for repurposed hardware. Other measures reduce but do not eliminate exposure: lower transmit power, reorient or shield antennas, and restrict coverage to physically trusted space to make adjacent access harder, accepting degraded coverage as a side effect; place the AP management interface on a segmented VLAN reachable only by administrators so a compromised radio-side process cannot pivot to management services; and monitor AP firmware logs for driver crashes or reboots that could indicate frame-level fuzzing or exploitation attempts, understanding that such logging detects rather than prevents the attack. Since exploitation is unauthenticated over the air and no public exploit code has been identified at time of analysis, prioritize patching access points on the network edge where radio range extends beyond controlled physical boundaries.

Affects your stack

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Technical ContextAI · show details

The vulnerability is a CWE-787 out-of-bounds write caused by an incorrect bounds check in the MediaTek WLAN driver that runs the access-point role on MediaTek Wi-Fi hardware. Because the driver parses 802.11 management/data frames received over the air, a malformed frame can drive a length or offset value past the end of an allocated buffer, and the resulting memory corruption can be shaped into privilege escalation on the device. The adjacent attack vector (AV:A) with PR:N/UI:N and high CIA impact (CVSS 8.8) reflects that the vulnerable code path is reachable purely from the radio interface without authentication, while the scope remains unchanged (S:U), meaning the impact is contained to the affected AP system. CPE data ties exposure to MediaTek's software development kit (cpe:2.3:a:mediatek:software_development_kit) and to OpenWrt 19.07.0 and 21.02.0 (cpe:2.3:o:openwrt:openwrt:19.07.0, cpe:2.3:o:openwrt:openwrt:21.02.0), i.e., downstream firmware images that embed the vulnerable MediaTek driver, which is why the advisory is published by MediaTek rather than by a single OEM.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (mediatek) PRIMARY 8.8 HIGH

AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vuln.today AI 8.8 HIGH

Wireless-range-only so AV:A; crafted frame needs no auth or interaction (PR:N/UI:N/AC:L); OOB write enabling privilege escalation yields C:H/I:H/A:H with scope unchanged.

3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

4.0 AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (mediatek).

CVSS VectorVendor: mediatek

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: WCNCR00422399; Issue ID: MSV-3748.

Executive ViewAI

Why It Matters

MediaTek WLAN access-point drivers used in MediaTek SDK-based firmware and OpenWrt 19.07.0/21.02.0 images expose organizations to a memory-corruption flaw that an unauthenticated attacker within wireless range could use to escalate privileges on affected access points. This can put wireless infrastructure and the networks behind it at risk, making affected AP inventory and mitigation a leadership concern even though no public exploit has been identified at time of analysis and a vendor fix is referenced by Patch ID WCNCR00422399 (MSV-3748).

Business Impact: High

Compensating Controls

No vendor-released patch identified at time of analysis; interim mitigations include disabling AP mode on affected MediaTek WLAN devices, restricting physical/wireless proximity, segregating AP management and wireless traffic, monitoring for crashes or anomalous behavior, and pursuing the referenced vendor fix Patch ID WCNCR00422399 (MSV-3748) through MediaTek/OEM channels.

Threat Intelligence Overview

EPSS Score

0.3%

Top 78% exploitable

Prevalence

High

MediaTek WLAN chipsets ubiquitous in routers/IoT; OpenWrt builds widely deployed

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.3%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Controlled

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Privilege Escalation HIGH

Privilege escalation occurs when an attacker leverages flaws in access control mechanisms to gain permissions beyond what they were originally granted.

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.