What is the CVSS score of CVE-2026-3703?

CVE-2026-3703 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.2%.

Is there a public PoC exploit available for CVE-2026-3703?

Yes, a public proof-of-concept exploit is available for CVE-2026-3703. Prioritise patching immediately. EPSS: 0.2%.

How to fix or mitigate CVE-2026-3703?

Within 24 hours: Identify and inventory all Wavlink NU516U1 devices in your environment and isolate them from production networks if possible. Within 7 days: Implement network segmentation to restrict access to the affected devices, disable remote management features, and monitor for exploitation attempts. Within 30 days: Develop a replacement or upgrade strategy with the vendor, and establish a timeline for decommissioning vulnerable devices once patches or alternatives are available.

Wl Nu516u1 Firmware CVE-2026-3703

CRITICAL

Buffer Overflow (CWE-119)

2026-03-08 cna@vuldb.com

Buffer Overflow Wl Nu516u1 Firmware Wavlink

9.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

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

Access

Send crafted HTTP request to /cgi-bin/login.cgi
Exploit

Manipulate ipaddr parameter with oversized input
Execution

Trigger out-of-bounds write in sub_401A10
Impact

Execute arbitrary code on device

Vulnerability Assessment

Weakness	CWE CWE-119 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, buffer size validation MITRE ATT&CK 2 techniques across 2 tactics: Execution,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	No special conditions — remote unauthenticated exploitation against Wavlink NU516U1 firmware 251208 with default /cgi-bin/login.cgi endpoint accessible.
Impact	CVSS 9.8 with PoC. Wavlink routers are commonly found in consumer networks.
Exploit ScenarioDerived	An attacker sends crafted HTTP requests to the CGI interface to overflow the buffer and gain code execution.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Wavlink NU516U1 firmware 251208 has a buffer overflow enabling remote code execution through crafted HTTP requests to the CGI interface.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:55 CVSS 9.8

Buffer overflow in Wavlink NU516U1 router enables RCE.

RemediationAI

Update firmware. Restrict management access.

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

Wavlink NU516U1 firmware 251208 has a CWE-119 memory corruption in sub_401A10 of /cgi-bin/adm.cgi.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

AV:N/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

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

PoC Detected

Mar 10, 2026 - 18:55 vuln.today

Public exploit code

CVE Published

Mar 08, 2026 - 05:16 nvd

CRITICAL 9.8

DescriptionCVE.org

A flaw has been found in Wavlink NU516U1 251208. This affects the function sub_401A10 of the file /cgi-bin/login.cgi. Executing a manipulation of the argument ipaddr can lead to out-of-bounds write. The attack may be performed from remote. The exploit has been published and may be used. Upgrading the affected component is recommended. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

Executive ViewAI

Why It Matters

A critical vulnerability (CVSS 9.8) in Wavlink NU516U1 network devices allows unauthenticated remote attackers to compromise affected systems through the login interface. Organizations using this device model face immediate risk of unauthorized access, data theft, and network infiltration, with active exploits already in the wild.

Business Impact: Severe

Compensating Controls

Implement network segmentation and firewall rules to restrict access to the /cgi-bin/login.cgi endpoint; disable remote management interfaces if operationally feasible; deploy WAF rules to block suspicious authentication attempts; enable detailed logging and SIEM monitoring for login.cgi access patterns; consider air-gapping affected devices until patching is available; evaluate vendor communications for interim firmware updates or security advisories.

Threat Intelligence Overview

EPSS Score

0.2%

Top 62% exploitable

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

VulDB

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 CRITICAL

CISA KEV No

Public POC Yes

EPSS 0.2%

Patch available No

Active threat No

Deciding rule

CRITICAL severity + public POC available

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

Out-of-Cycle

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +49

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

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.