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CVE-2021-27289

9.1 · CRITICAL

A replay attack vulnerability was discovered in a Zigbee smart home kit manufactured by Ksix (Zigbee Gateway Module = v1.0.3, Door Sensor = v1.0.7, Motion Sensor = v1.0.12), where the Zigbee anti-r…

Published Apr 15, 2025CWE-294EPSS 0.85%

Overview

CVE-2021-27289 is a critical-severity vulnerability. It was published on April 15, 2025 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

A replay attack vulnerability was discovered in a Zigbee smart home kit manufactured by Ksix (Zigbee Gateway Module = v1.0.3, Door Sensor = v1.0.7, Motion Sensor = v1.0.12), where the Zigbee anti-replay mechanism - based on the frame counter field - is improperly implemented. As a result, an attacker within wireless range can resend captured packets with a higher sequence number, which the devices incorrectly accept as legitimate messages. This allows spoofed commands to be injected without authentication, triggering false alerts and misleading the user through notifications in the mobile application used to monitor the network.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/TheMalwareGuardian/CVE-2021-27289Refpacketstormsecurity.com/files/160331/Ksix-Zigbee-Devices-Playback-Protection-Bypass.htmlRefwww.exploit-db.com/exploits/49169Refwww.youtube.com/watch?v=5IFUpRKEioARefwww.youtube.com/watch?v=XFOy3wSlC9QRefwww.youtube.com/watch?v=yc9IEt5IMmA

How CyberStrike helps

Frequently asked questions

What is CVE-2021-27289?

CVE-2021-27289 is a critical-severity vulnerability. It was published on April 15, 2025 and has a CVSS 3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2021-27289?

This vulnerability has a CVSS 3.1 base score of 9.1, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-27289?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-27289?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-27289 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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