CVE-2021-44415 – This vulnerability allows remote attackers to c... (How to Fix)

Q: What is the severity of CVE-2021-44415?

CVE-2021-44415 has a CVSS score of 7.7 (HIGH). This vulnerability allows remote attackers to cause a denial of service by sending a specially crafted HTTP request to the Reolink RLC-410W camera's cgiserver.cgi JSON command parser. When exploited, it forces the device to reboot, disrupting camera functionality. This affects Reolink RLC-410W cameras running vulnerable firmware.

📋 TL;DR

This vulnerability allows remote attackers to cause a denial of service by sending a specially crafted HTTP request to the Reolink RLC-410W camera's cgiserver.cgi JSON command parser. When exploited, it forces the device to reboot, disrupting camera functionality. This affects Reolink RLC-410W cameras running vulnerable firmware.

💻 Affected Systems

Products:

Reolink RLC-410W

Versions: v3.0.0.136_20121102

Operating Systems: Embedded Linux firmware

Default Config Vulnerable: ⚠️ Yes

Notes: Affects the specific firmware version mentioned; other Reolink models may have similar vulnerabilities but are not confirmed for this CVE.

📦 What is this software?

Rlc 410w Firmware by Reolink

View all CVEs affecting Rlc 410w Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Persistent attacker could repeatedly reboot the camera, rendering it unusable for extended periods and potentially causing physical security monitoring gaps.

🟠

Likely Case

Temporary camera unavailability during reboot cycles, causing missed surveillance footage and operational disruption.

🟢

If Mitigated

Minimal impact with proper network segmentation and access controls preventing external exploitation.

🌐 Internet-Facing: HIGH - The vulnerability is exploitable via HTTP requests, making internet-exposed devices particularly vulnerable to automated attacks.

🏢 Internal Only: MEDIUM - Internal attackers or compromised internal systems could exploit this, but requires network access to the camera.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The Talos Intelligence report includes technical details that could be used to create exploit code. The vulnerability requires sending a malformed HTTP request with incorrect JSON structure.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check Reolink for updated firmware

Vendor Advisory: https://reolink.com/support/security-advisory/

Restart Required: Yes

Instructions:

1. Log into Reolink camera web interface. 2. Navigate to System > Maintenance > Firmware Upgrade. 3. Download latest firmware from Reolink website. 4. Upload and apply firmware update. 5. Camera will reboot automatically.

🔧 Temporary Workarounds

Network Segmentation

all

Place cameras on isolated VLAN without internet access

Access Control Lists

linux

Restrict HTTP access to camera management interface to trusted IPs only

iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP

🧯 If You Can't Patch

Implement strict network segmentation to isolate cameras from untrusted networks
Deploy web application firewall (WAF) rules to block malformed JSON requests to cgiserver.cgi

🔍 How to Verify

Check if Vulnerable:

Check firmware version in camera web interface under System > Device Information

Check Version:

curl -s http://CAMERA_IP/cgi-bin/cgiserver.cgi?cmd=getDevInfo | grep version

Verify Fix Applied:

Confirm firmware version is newer than v3.0.0.136_20121102 and test with controlled exploit attempt

📡 Detection & Monitoring

Log Indicators:

Multiple reboot events in system logs
HTTP requests to cgiserver.cgi with malformed JSON

Network Indicators:

HTTP POST requests to /cgi-bin/cgiserver.cgi with ModifyUser parameter
Unusual reboot patterns from camera IP

SIEM Query:

source="camera_logs" AND (event="reboot" OR uri="/cgi-bin/cgiserver.cgi") | stats count by src_ip

📊 Metadata

CVE ID: CVE-2021-44415

CVSS v3 Score: 7.7 (HIGH)

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

CWE: CWE-20

Published: January 28, 2022

Last Updated: November 21, 2024

🔗 References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1421 Exploit,Technical Description,Third Party Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1421 Exploit,Technical Description,Third Party Advisory

📤 Share & Export

📄 Export Markdown 📋 Export JSON

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