CVE-2021-44419 – A denial-of-service vulnerability in Reolink RL... (How to Fix)

Q: What is the severity of CVE-2021-44419?

CVE-2021-44419 has a CVSS score of 7.7 (HIGH). A denial-of-service vulnerability in Reolink RLC-410W cameras allows attackers to cause device reboots via specially crafted HTTP requests targeting the GetMdAlarm parameter. This affects Reolink RLC-410W v3.0.0.136_20121102 cameras exposed to network access.

📋 TL;DR

A denial-of-service vulnerability in Reolink RLC-410W cameras allows attackers to cause device reboots via specially crafted HTTP requests targeting the GetMdAlarm parameter. This affects Reolink RLC-410W v3.0.0.136_20121102 cameras exposed to network access.

💻 Affected Systems

Products:

Reolink RLC-410W

Versions: v3.0.0.136_20121102

Operating Systems: Embedded firmware

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects the specific firmware version mentioned; other versions may be unaffected.

📦 What is this software?

Rlc 410w Firmware by Reolink

View all CVEs affecting Rlc 410w Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Persistent denial-of-service attacks causing repeated reboots, rendering the camera unavailable for surveillance purposes.

🟠

Likely Case

Temporary camera unavailability during reboot cycles, disrupting video monitoring.

🟢

If Mitigated

No impact if cameras are isolated from untrusted networks or patched.

🌐 Internet-Facing: HIGH - Directly accessible cameras can be rebooted by anyone with network access.

🏢 Internal Only: MEDIUM - Internal attackers or compromised internal systems could exploit this vulnerability.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires sending a malformed HTTP request to the cgiserver.cgi endpoint with invalid GetMdAlarm parameter.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Later firmware versions (check Reolink for specific fixed version)

Vendor Advisory: https://www.reolink.com/security/

Restart Required: Yes

Instructions:

1. Log into Reolink camera web interface. 2. Navigate to System > Maintenance > Firmware Upgrade. 3. Upload latest firmware from Reolink website. 4. Wait for automatic reboot.

🔧 Temporary Workarounds

Network Segmentation

all

Isolate cameras from untrusted networks using firewall rules.

Access Control Lists

all

Restrict HTTP access to camera management interface to trusted IPs only.

🧯 If You Can't Patch

Place cameras on isolated VLAN with no internet access
Implement network monitoring for HTTP requests to cgiserver.cgi with malformed parameters

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

Check via web interface or use curl to query device information endpoint

Verify Fix Applied:

Confirm firmware version is newer than v3.0.0.136_20121102 and test with proof-of-concept exploit.

📡 Detection & Monitoring

Log Indicators:

HTTP requests to /cgi-bin/cgiserver.cgi with malformed GetMdAlarm parameter
Unexpected device reboots

Network Indicators:

HTTP POST requests to camera IP on port 80 with JSON payload containing GetMdAlarm parameter

SIEM Query:

sourceIP="camera_ip" AND destPort=80 AND httpMethod=POST AND uri="/cgi-bin/cgiserver.cgi" AND httpContent LIKE "%GetMdAlarm%"

📊 Metadata

CVE ID: CVE-2021-44419

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

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