Reolink RLC-410W IP Camera SetDdns API OS Command Injection Vulnerability (CVE-2021-40407) Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTReolink RLC-410W smart IP camera firmware version v3.0.0.136_20121102 and prior
An authenticated attacker can execute arbitrary OS commands with root privileges by sending a crafted HTTP request, leading to complete device compromise
Immediately update to the latest official secure firmware and restrict external access to the camera management interface
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Download the latest secure firmware from the official Reolink Download Center. You can verify the current firmware version of your device using the following API query command:
# Query the camera API to retrieve system information and verify the firmware version
curl -s -k -X POST -d '[{"cmd":"GetAbility","action":0,"param":{}}]' \
'https://<CAMERA_IP>/cgi-bin/api.cgi?user=admin&password=<PASSWORD>' \
| grep -i 'firmware'2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, isolate the camera from the public internet and restrict access to the management ports (HTTP/HTTPS, RTSP). Below is an example of iptables rules to restrict access to trusted administrative subnets only:
# Block all public access to the camera web ports (80, 443)
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
# Allow access only from a trusted management subnet (e.g., 192.168.1.0/24)
iptables -I INPUT -s 192.168.1.0/24 -p tcp --dport 80 -j ACCEPT
iptables -I INPUT -s 192.168.1.0/24 -p tcp --dport 443 -j ACCEPT3. Log Audit & IoC Verification Commands
Monitor network traffic and web server logs for suspicious SetDdns API requests containing shell metacharacters. Use the following command to scan access logs for potential exploitation attempts:
# Scan web server access logs for SetDdns requests containing shell metacharacters
grep -E 'SetDdns' /var/log/nginx/access.log | grep -E '(%3B|%26|%7C|%60|;|\&|\||`)'Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
An OS command injection vulnerability (CVE-2021-40407) exists in the device network settings functionality of the Reolink RLC-410W IP camera. The root cause lies in the improper validation of the domain parameter supplied via the SetDdns API. The value is stored in the ddns->domain variable and subsequently executed within a system shell context without adequate sanitization, allowing malicious shell metacharacters to be processed.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first obtain authenticated access to the camera's web management interface or API. The attacker then transmits a specially crafted HTTP POST request targeting the SetDdns API. By embedding shell metacharacters (such as ;, &, or ` `) along with arbitrary Linux commands inside the domain` parameter, the attacker forces the underlying operating system to execute the injected commands under root privileges.
3. Infrastructure & Business Impact
This vulnerability is rated CVSS 7.2 (High) and is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild. Successful exploitation allows threat actors to hijack video streams, recruit the device into IoT botnets for DDoS campaigns, or use the compromised camera as a pivot point to compromise the internal corporate network.
Official Vendor Advisories & References
An OS command injection vulnerability exists in the device network settings functionality of reolink RLC-410W v3.0.0.136_20121102. At [1] or [2], based on DDNS type, the ddns->domain variable, that has the value of the domain parameter provided through the SetDdns API, is not validated properly. This would lead to an OS command injection. An attacker can send an HTTP request to trigger this vulnerability.
Frequently Asked SecOps Questions (CVE-2021-40407)
FAQQ1. How critical is CVE-2021-40407 and is it actively exploited in the wild?
CVE-2021-40407 is rated CVSS 7.2 (HIGH) with a 30-day EPSS exploitation probability of 47.6%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-40407?
Primary impacted vendors include reolink across rlc-410w. Scope summary: Reolink RLC-410W IP camera firmware version v3.0.0.136_20121102 and earlier
Q3. What temporary mitigations or workarounds exist for CVE-2021-40407 before patching?
[Mitigation] Immediately update to the latest official secure firmware and restrict external access to the camera management interface Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2021-40407
Instantly format this advisory into an executive CISO summary or engineering patch ticket.
🔗 Related Advisories in Similar Stack (reolink)
View Category →LiteLLM Proxy Server MCP Test Endpoints Remote Code Execution Vulnerability Advisory (CVE-2026-42271)
[Affected Scope] LiteLLM proxy server environments running versions 1.74.2 to before 1.83.7
Apple macOS Screen Sharing Authentication Bypass Vulnerability (CVE-2026-65400)
[Affected Scope] macOS systems running versions prior to Sequoia 15.7.9, Sonoma 14.8.9, Tahoe 26.6.1/26.7, or Golden Gate 27 with Screen Sharing or VNC services enabled
DAEMON Tools Lite Official Installer Supply Chain Attack and Trojanized Binaries (CVE-2026-8398)
[Affected Scope] DAEMON Tools Lite Windows versions 12.5.0.2421 through 12.5.0.2434 distributed between April 8, 2026, and May 5, 2026
Microsoft Windows Shell Command Injection and Security Feature Bypass (CVE-2026-96951) Advisory
[Affected Scope] All supported versions of Windows OS including Windows 10, 11, and Windows Server.
Subscribe to Daily Vulnerability Briefings & KEV Alerts
Concise morning briefings for SecOps, DevSecOps, and SRE teams covering newly exploited CVEs and mitigation priorities.