CVE-2021-27289Public exploit

Authentication bypass via unchecked Zigbee frame counters

Published Apr 15, 2025 · Updated Apr 16, 2025

Authentication bypass in Ksix Zigbee smart home kit devices allows physically proximate attackers to inject spoofed commands. The Zigbee stack accepts captured frames with increased sequence numbers because it does not correctly validate the anti-replay frame counter. Wireless range and a previously captured valid frame are required; successful replay creates false door or motion alerts in the monitoring app.

CVSS severity9.1
Critical
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Ksix Zigbee smart home kit devices allows physically proximate attackers to inject spoofed commands. The Zigbee stack accepts captured frames with increased sequence numbers because it does not correctly validate the anti-replay frame counter. Wireless range and a previously captured valid frame are required; successful replay creates false door or motion alerts in the monitoring app.

The record

CVE
CVE-2021-27289
Published
Apr 15, 2025
Updated
Apr 16, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-294, T1565.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-294Authentication Bypass by Capture-replay
T1565.002Transmitted Data Manipulation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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