What is the CVSS score of CVE-2026-20408?

CVE-2026-20408 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: 0.0%.

How to fix or mitigate CVE-2026-20408?

Within 24 hours: Identify all affected WLAN equipment in inventory and isolate critical networks from compromised access points; notify all users of temporary access restrictions. Within 7 days: Implement network segmentation to restrict lateral movement, enable enhanced wireless monitoring/logging, and contact vendor for patch timeline or alternative solutions. Within 30 days: Deploy compensating controls (see below), conduct network security assessment, and establish contingency plan for equipment replacement if patch remains unavailable.

Openwrt CVE-2026-20408

HIGH

Heap-based Buffer Overflow (CWE-122)

2026-02-02 security@mediatek.com

Privilege Escalation Buffer Overflow Mediatek Openwrt Software Development Kit

8.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

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

Access

Send crafted wireless frame
Exploit

Trigger heap buffer overflow in WLAN parser
Execution

Write arbitrary memory
Impact

Escalate privilege on target device

Vulnerability Assessment

Weakness	CWE CWE-122 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Heap buffer bounds checking MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list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	Adjacent network proximity required. Target device must have WLAN functionality enabled and be within radio range of attacker. No authentication or user interaction needed. Affects default WLAN configurations.
Impact	CVSS 8.8 (HIGH). Attack vector: Adjacent Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitable via remote/network.
Exploit ScenarioDerived	A remote attacker could exploit this vulnerability to remote (proximal/adjacent) escalation of privilege with no additional execution.

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

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

OpenWRT and related SDKs are vulnerable to a heap buffer overflow in the WLAN component that allows adjacent network attackers to execute privilege escalation without user interaction or special permissions. The out-of-bounds write condition enables attackers on the same network segment to gain elevated system privileges. No patch is currently available for this vulnerability.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:01 CVSS 8.8

In wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. [CVSS 8.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-122 (Heap-based Buffer Overflow). Affects Software Development Kit. In wlan, there is a possible out of bounds write due to a heap buffer overflow. 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: WCNCR00461651; Issue ID: MSV-4758.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

Executive ViewAI

Why It Matters

A critical wireless LAN vulnerability (CVE-2026-20408) allows attackers with network proximity to execute privilege escalation attacks, potentially compromising connected devices and sensitive data. Without a vendor patch available, immediate risk mitigation and network containment measures are required to prevent unauthorized access to systems connected through affected wireless infrastructure.

Business Impact: High

Compensating Controls

Disable non-essential WLAN features until patch availability; implement strict network segmentation isolating wireless from critical systems; deploy intrusion detection/prevention systems (IDS/IPS) with vulnerability-specific signatures; enforce WPA3 encryption and MAC filtering where supported; restrict wireless access to essential personnel only; enable continuous wireless security monitoring and anomaly detection; consider temporary deployment of alternative wired connectivity for critical systems; require multi-factor authentication for all wireless network access.

Threat Intelligence Overview

EPSS Score

0.0%

Top 100% exploitable

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 0.0%

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.