Is CVE-2021-21959 actively exploited?

No active exploitation of CVE-2021-21959 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21959 be exploited remotely?

Yes. CVE-2021-21959 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21959?

CVE-2021-21959 has a CVSS score of 8.1 (HIGH).

HOME VULNERABILITIESCVE-2021-21959

HIGH

CVE-2021-21959

CWE-295Published: February 4, 2022· Updated: Jun 17, 2026

8.1

CVSS v3.1

Official Description

A misconfiguration exists in the MQTTS functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. This misconfiguration significantly simplifies a man-in-the-middle attack, which directly leads to control of device functionality.

NVD Source

Technical Analysis

CVE-2021-21959 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 complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.1.