Is CVE-2021-21967 actively exploited?

No active exploitation of CVE-2021-21967 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21967 be exploited remotely?

Yes. CVE-2021-21967 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21967?

CVE-2021-21967 has a CVSS score of 5.9 (MEDIUM).

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MEDIUM

CVE-2021-21967

CWE-120Published: April 14, 2022· Updated: Jun 17, 2026

5.9

CVSS v3.1

Official Description

An out-of-bounds write vulnerability exists in the OTA update task functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. A specially-crafted MQTT payload can lead to denial of service. An attacker can perform a man-in-the-middle attack to trigger this vulnerability.

NVD Source

Technical Analysis

CVE-2021-21967 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 5.9.