Is CVE-2021-27954 actively exploited?

No active exploitation of CVE-2021-27954 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-27954 be exploited remotely?

Yes. CVE-2021-27954 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-27954?

CVE-2021-27954 has a CVSS score of 8.2 (HIGH).

HOME VULNERABILITIESCVE-2021-27954

HIGH

CVE-2021-27954

CWE-787Published: August 3, 2021· Updated: Jun 17, 2026

8.2

CVSS v3.1

Official Description

A heap-based buffer overflow vulnerability exists on the ecobee3 lite 4.5.81.200 device in the HKProcessConfig function of the HomeKit Wireless Access Control setup process. A threat actor can exploit this vulnerability to force the device to connect to a SSID or cause a denial of service.

NVD Source

Technical Analysis

CVE-2021-27954 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 8.2.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.