What is the CVSS score of CVE-2026-4181?

CVE-2026-4181 has a CVSS 4.0 base score of 8.9 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-4181?

Yes, a public proof-of-concept exploit is available for CVE-2026-4181. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-4181?

Within 24 hours: Audit network inventory to identify all DIR-816 1.10CNB05 devices and isolate them from production networks. Within 7 days: Develop decommissioning plan for affected devices and procure replacement hardware from supported vendors. Within 30 days: Complete replacement of all vulnerable devices and validate network segmentation controls are in place.

Dir 816 CVE-2026-4181

EUVD-2026-12233 HIGH

Stack-based Buffer Overflow (CWE-121)

2026-03-15 VulDB

Buffer Overflow D-Link Stack Overflow Dir 816 D-Link

8.9

CVSS 4.0 · NVD

View

Attack ChainAIDerived

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

Access

Send crafted HTTP request to /goform/form2RepeaterStep2.cgi
Exploit

Inject oversized payload into key1/key2/key3/key4/pskValue parameters
Execution

Trigger stack-based buffer overflow in goahead
Impact

Execute arbitrary code on router

Vulnerability Assessment

Weakness	CWE CWE-121 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Stack buffer bounds checking MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list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	D-Link DIR-816 firmware version 1.10CNB05 with goahead web server enabled and /goform/form2RepeaterStep2.cgi endpoint accessible. No authentication required; default configurations vulnerable. Product no longer receives security updates from maintainer.
Impact	This vulnerability presents an extremely high real-world risk. The CVSS 3.1 score of 9.8 reflects network-accessible (AV:N), low complexity (AC:L) attacks requiring no privileges (PR:N) or user interaction (UI:N). The CVSS vector indicates proof-of-concept code exists (E:P) and the vulnerability is confirmed (RC:R). While EPSS and KEV data are not provided, the availability of a public exploit on GitHub significantly increases exploitation likelihood. The fact that these are unsupported devices (RL:X) means no patches will be released, making any deployed units permanently vulnerable. This combination of factors - remote exploitation, no authentication required, public exploit, and no patch availability - makes this a critical priority for immediate action.
Exploit ScenarioDerived	An attacker can remotely exploit this vulnerability by sending specially crafted HTTP requests to the router's web interface at /goform/form2RepeaterStep2.cgi. By manipulating the key1-4 or pskValue parameters with oversized input, the attacker triggers a stack buffer overflow, potentially executing arbitrary code with the privileges of the goahead web server. Since authentication is not required and a working exploit is publicly available at https://github.com/wudipjq/my_vuln/blob/main/D-Link7/vuln_85/85.md, this attack can be automated and executed at scale against internet-facing DIR-816 devices.

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

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

Critical stack-based buffer overflow vulnerability in the D-Link DIR-816 router (firmware version 1.10CNB05) that allows remote attackers to execute arbitrary code without authentication. A public proof-of-concept exploit is available, and the vulnerability affects end-of-life products no longer supported by D-Link, making this a high-risk issue for organizations still using these devices.

RemediationAI

Since D-Link no longer supports the DIR-816 product line, no official patches will be released. Organizations must immediately replace these devices with supported alternatives. As an emergency mitigation, block external access to the device's web interface and restrict management access to trusted IP addresses only. However, given the critical nature and public exploit availability, device replacement is the only reliable remediation. Check D-Link's official website (https://www.dlink.com/) for recommended replacement models.

Affected VersionsENISA

DIR-816 1.10CNB05

Affected Packages

euvd dir_816 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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

Technical ContextAI · show details

The vulnerability exists in the goahead web server component, specifically in the /goform/form2RepeaterStep2.cgi file. According to the CPE identifier (cpe:2.3:a:d-link:dir-816:*:*:*:*:*:*:*:*), all versions of the DIR-816 router are affected. The root cause is CWE-121 (Stack-based Buffer Overflow), where improper validation of input parameters (key1, key2, key3, key4, and pskValue) allows an attacker to overflow the stack buffer, potentially overwriting return addresses and gaining control of execution flow.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.9 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

None

User Interaction

None

Vulnerable system: Confidentiality

High

Vulnerable system: Integrity

High

Vulnerable system: Availability

High

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

Lifecycle Timeline

PoC Detected

Apr 06, 2026 - 14:12 vuln.today

Public exploit code

CVE Published

Mar 15, 2026 - 16:02 nvd

HIGH 8.9

DescriptionCVE.org

A security flaw has been discovered in D-Link DIR-816 1.10CNB05. This affects an unknown function of the file /goform/form2RepeaterStep2.cgi of the component goahead. The manipulation of the argument key1/key2/key3/key4/pskValue results in stack-based buffer overflow. The attack may be launched remotely. The exploit has been released to the public and may be used for attacks. This vulnerability only affects products that are no longer supported by the maintainer.

Executive ViewAI

Why It Matters

A critical remote code execution vulnerability (CVE-2026-4181, CVSS 9.8) affects D-Link DIR-816 routers running firmware 1.10CNB05 with no patch available. Active public exploits exist, creating immediate risk for any organizations still deploying this end-of-life device. Attackers can achieve unauthenticated remote code execution, potentially compromising network integrity and sensitive data.

Business Impact: Severe

Compensating Controls

Network segmentation to restrict access to affected devices; disable remote management access if possible; deploy WAF rules to block requests to /goform/form2RepeaterStep2.cgi; implement network-based IPS signatures to detect exploitation attempts; consider blocking device internet access if business function permits; monitor for suspicious outbound connections from device IP ranges.

Threat Intelligence Overview

EPSS Score

0.1%

Top 81% exploitable

Exploit

POC

Public exploit code exists

Data Quality

6 sources

Confidence: High

EUVD

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 HIGH

CISA KEV No

Public POC Yes

EPSS 0.1%

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

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: +44

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.

Stack-based Buffer Overflow HIGH

A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.