What’s Vulnerable › Vulnerabilities

CVE-2021-27289

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-04-15 · updated 2026-06-17
• Weakness: CWE-294

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.

References

• https://github.com/TheMalwareGuardian/CVE-2021-27289
• https://packetstormsecurity.com/files/160331/Ksix-Zigbee-Devices-Playback-Protection-Bypass.html
• https://www.exploit-db.com/exploits/49169
• https://www.youtube.com/watch?v=5IFUpRKEioA
• https://www.youtube.com/watch?v=XFOy3wSlC9Q
• https://www.youtube.com/watch?v=yc9IEt5IMmA

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