What is the CVSS score of CVE-2021-27289?

CVE-2021-27289 has a CVSS 3.1 base score of 9.1 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H. EPSS exploitation probability: 0.6%.

Is there a public PoC exploit available for CVE-2021-27289?

Yes, a public proof-of-concept exploit is available for CVE-2021-27289. Prioritise patching immediately. EPSS: 0.6%.

How to fix or mitigate CVE-2021-27289?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Monitor vendor channels for patch availability.

CVE-2021-27289

CRITICAL

Authentication Bypass by Capture-replay (CWE-294)

2025-04-15 cve@mitre.org

Code Injection

9.1

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.1 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:36 vuln.today

PoC Detected

Apr 16, 2025 - 15:15 vuln.today

Public exploit code

CVE Published

Apr 15, 2025 - 18:15 nvd

CRITICAL 9.1

DescriptionCVE.org

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.

AnalysisAI

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. Rated critical severity (CVSS 9.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified under CWE-294. 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.

Affected ProductsAI

See vendor advisory for affected versions.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.