What is CVE-2021-27289?

CVE-2021-27289 is a critical-severity vulnerability in N/a, classified under Authentication Bypass by Capture-replay. CVSS score: 9.1/10. Published 2025-04-15.

How severe is CVE-2021-27289?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Is CVE-2021-27289 known to be exploited?

3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in N/a

CVE-2021-27289

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.

EPSS: 0.008 (53.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H.

Affected products

N/a — versions n/a

Weakness classification (CWE)

CWE-294 — Authentication Bypass by Capture-replay

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-27289?: CVE-2021-27289 is a critical-severity vulnerability in N/a, classified under Authentication Bypass by Capture-replay. CVSS score: 9.1/10. Published 2025-04-15.
How severe is CVE-2021-27289?: Critical severity. CVSS v3 base score is 9.1 out of 10.
Is CVE-2021-27289 known to be exploited?: 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.