CVE-2021-41441 – This vulnerability allows remote attackers to c... (How to Fix)

Q: What is the severity of CVE-2021-41441?

CVE-2021-41441 has a CVSS score of 7.4 (HIGH). This vulnerability allows remote attackers to cause a denial-of-service (DoS) by tricking an authenticated user into visiting a specially crafted URL, which triggers a router reboot. It affects D-Link DIR-X1860 routers running firmware versions before v1.10WWB09_Beta. The attack requires social engineering to get an authenticated victim to click the malicious link.

📋 TL;DR

This vulnerability allows remote attackers to cause a denial-of-service (DoS) by tricking an authenticated user into visiting a specially crafted URL, which triggers a router reboot. It affects D-Link DIR-X1860 routers running firmware versions before v1.10WWB09_Beta. The attack requires social engineering to get an authenticated victim to click the malicious link.

💻 Affected Systems

Products:

D-Link DIR-X1860

Versions: All versions before v1.10WWB09_Beta

Operating Systems: Router firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations of affected firmware versions are vulnerable. No special configuration required for exploitation.

📦 What is this software?

Dir X1860 Firmware by Dlink

View all CVEs affecting Dir X1860 Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Persistent DoS attacks could render the router unusable for extended periods, disrupting all network connectivity for connected devices and potentially causing service outages.

🟠

Likely Case

Temporary network disruption when router reboots, causing brief connectivity loss for all connected devices (typically 1-2 minutes).

🟢

If Mitigated

Minimal impact with proper user awareness training and network segmentation limiting exposure.

🌐 Internet-Facing: MEDIUM - Attackers can craft malicious URLs but require social engineering to get authenticated users to visit them.

🏢 Internal Only: LOW - Same attack vector applies regardless of network location; risk depends on user behavior not network segmentation.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires social engineering to get authenticated users to click malicious URLs. The technical exploit itself is simple once the URL is crafted.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: v1.10WWB09_Beta or later

Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10283

Restart Required: Yes

Instructions:

1. Log into router admin interface. 2. Navigate to firmware update section. 3. Download v1.10WWB09_Beta or later from D-Link support site. 4. Upload and install the firmware. 5. Router will reboot automatically after update.

🔧 Temporary Workarounds

User Awareness Training

all

Educate users not to click unknown URLs, especially while authenticated to router admin interface.

Restrict Admin Access

linux

Limit router admin interface access to specific IP addresses or VLANs only.

Configure firewall rules to restrict access to router admin port (typically 80/443)

🧯 If You Can't Patch

Implement network segmentation to isolate router management interface from general user networks
Deploy web filtering to block malicious URLs and educate users about phishing risks

🔍 How to Verify

Check if Vulnerable:

Check router firmware version in admin interface under System > Firmware

Check Version:

Login to router web interface and navigate to System > Firmware section

Verify Fix Applied:

Confirm firmware version shows v1.10WWB09_Beta or higher after update

📡 Detection & Monitoring

Log Indicators:

Multiple router reboot events in system logs
Unusual URL access patterns in web server logs

Network Indicators:

Sudden loss of router connectivity followed by reboot
Unusual HTTP requests to router web interface

SIEM Query:

source="router_logs" AND (event="reboot" OR event="system_restart") | stats count by src_ip

📊 Metadata

CVE ID: CVE-2021-41441

CVSS v3 Score: 7.4 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H

CWE: CWE-404

Published: February 9, 2022

Last Updated: November 21, 2024

🔗 References

http://d-link.com Broken Link
http://dir-x1860.com Broken Link,URL Repurposed
https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10283 Patch,Technical Description,Vendor Advisory
https://www.dlink.com/en/security-bulletin/ Vendor Advisory
http://d-link.com Broken Link
http://dir-x1860.com Broken Link,URL Repurposed
https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10283 Patch,Technical Description,Vendor Advisory
https://www.dlink.com/en/security-bulletin/ Vendor Advisory

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🔗 Related Vulnerabilities

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