What is the CVSS score of EUVD-2026-20809?

EUVD-2026-20809 has a CVSS 4.0 base score of 7.4 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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 EUVD-2026-20809?

Yes, a public proof-of-concept exploit is available for EUVD-2026-20809. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate EUVD-2026-20809?

Within 24 hours: Identify all D-Link DIR-645 devices on the network using inventory tools and determine business-critical vs. non-critical deployments. Within 7 days: Implement network segmentation-isolate affected routers to a restricted management VLAN with access controls limiting administrative traffic only. Within 30 days: Complete replacement of all DIR-645 units with current, vendor-supported router models and validate connectivity before decommissioning legacy devices.

Dir 645 EUVD-2026-20809

| CVE-2026-5815 HIGH

Stack-based Buffer Overflow (CWE-121)

2026-04-08 VulDB

Buffer Overflow D-Link Stack Overflow Dir 645 D-Link

7.4

CVSS 4.0 · Vendor: VulDB

View

Attack ChainAIDerived

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

Access

Send authenticated request to /cgi-bin/hedwig.cgi
Exploit

Craft oversized input parameter
Execution

Trigger stack buffer overflow
Impact

Execute arbitrary code on router

Vulnerability Assessment

Weakness	CWE CWE-121 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	Requires authenticated access to D-Link DIR-645 router firmware versions 1.01, 1.02, or 1.03. Attacker must have valid login credentials to access the /cgi-bin/hedwig.cgi endpoint. No victim interaction needed. Remote exploitation possible. Products no longer supported by D-Link.
Impact	Stack buffer overflow in end-of-life D-Link router requiring authenticated access limits immediate blast radius to compromised networks. CVSS 7.4 reflects high confidentiality/integrity impact. Public exploit availability elevates risk for legacy infrastructure operators. Legacy product status means no vendor patches; mitigation depends entirely on network segmentation and access controls.
Exploit ScenarioDerived	Authenticated attacker sends oversized payload to /cgi-bin/hedwig.cgi, triggering stack overflow in hedwigcgi_main function. Overflow overwrites return pointer, enabling code execution with router privileges. Publicly available exploit code exists, lowering attack complexity.

Monitor Track and reassess. Why: Vendor states no customer action required.

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 08, 2026

Stack-based buffer overflow in D-Link DIR-645 router (versions 1.01, 1.02, 1.03) via hedwigcgi_main function in /cgi-bin/hedwig.cgi allows authenticated remote attackers to achieve complete system compromise. Exploitation requires low-privilege credentials but no user interaction. Publicly available exploit code exists. Product is end-of-life with no vendor support, making remediation limited to device replacement or network isolation.

RemediationAI

No vendor-released patch identified at time of analysis; D-Link has discontinued support for DIR-645 hardware per vendor statement. Primary recommendation: replace device with currently supported router model from active product line. Interim mitigation: disable remote administration interfaces, restrict /cgi-bin/hedwig.cgi access via firewall ACLs permitting only trusted management IPs, implement network segmentation isolating device from critical assets, enforce strong authentication credentials, monitor for unauthorized access attempts. Consult D-Link EOL policy and migration guidance at https://www.dlink.com/. Detailed technical writeup and proof-of-concept analysis available at https://github.com/Pers1st0/CVE/blob/main/stack-based%20buffer%20overflow%20vulnerability%20exists%20in%20the%20hedwig.cgi%20of%20D-Link%20DIR-645.md and https://vuldb.com/vuln/356263.

Affected VersionsENISA

DIR-645 1.02

DIR-645 1.03

DIR-645 1.01

Affected Packages

euvd dir_645 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

CWE-121 stack-based buffer overflow triggered through unsanitized input to hedwigcgi_main handler in hedwig.cgi CGI script. CVSS 4.0 vector PR:L indicates authenticated attack vector. Affects CPE cpe:2.3:a:d-link:dir-645 across firmware versions 1.01-1.03. Overflow enables arbitrary code execution in router context.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (VulDB) PRIMARY 7.4 HIGH

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

Primary rating from Vendor (VulDB) · only source for this CVE.

CVSS VectorVendor: VulDB

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

None

Privileges Required

Low

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 09, 2026 - 00:16 vuln.today

Public exploit code

CVE Published

Apr 08, 2026 - 23:15 nvd

HIGH 7.4

DescriptionCVE.org

A vulnerability was detected in D-Link DIR-645 1.01/1.02/1.03. Impacted is the function hedwigcgi_main of the file /cgi-bin/hedwig.cgi. The manipulation results in stack-based buffer overflow. The attack can be launched remotely. The exploit is now public and may be used. This vulnerability only affects products that are no longer supported by the maintainer.

Executive ViewAI

Why It Matters

D-Link DIR-645 routers (versions 1.01-1.03) contain a stack-based buffer overflow in the web interface that allows authenticated attackers to gain complete control of the device. This affects organizations still operating these end-of-life routers, creating an unpatched remote code execution risk that cannot be remediated through vendor updates. Immediate network isolation or replacement is required to prevent lateral movement into critical infrastructure.

Business Impact: High

Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Restrict administrative access to the router's web interface (/cgi-bin/hedwig.cgi) using firewall rules-allow only trusted administrative IP ranges; (2) Disable remote management if not operationally required; (3) Enforce network segmentation so compromised routers cannot pivot to sensitive systems; (4) Monitor for suspicious authentication attempts and command execution on affected devices; (5) Implement replacement roadmap with timeline not to exceed 90 days given end-of-life status and lack of patching capability.

Threat Intelligence Overview

EPSS Score

0.1%

Top 75% exploitable

Exploit

POC

Public exploit code exists

Social Media

Sightings

Data Quality

8 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment CIRCL

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

Vendor states no customer action required

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

Scheduled

Exploitation

Poc

System Exposure· derived

Open

Automatable

Human Impact

High

Technical Impact

Total

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +37

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.