How severe is CVE-2021-21959?

CVE-2021-21959 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21959 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21959?

CVE-2021-21959 affects Sealevel Seaconnect 370w Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21959?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-21959 published?

CVE-2021-21959 was published on 2022-02-04 and last updated on 2026-06-17.

CVE-2021-21959

CVE-2021-21959 is a high-severity vulnerability in Sealevel Seaconnect 370w Firmware with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v2: 6.8
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Sealevel Seaconnect 370w Firmware
Published: 2022-02-04
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-21959?: 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.
How severe is CVE-2021-21959?: CVE-2021-21959 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21959 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21959?: CVE-2021-21959 affects Sealevel Seaconnect 370w Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21959?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-21959 published?: CVE-2021-21959 was published on 2022-02-04 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1388

Affected products (1)

cpe:2.3:o:sealevel:seaconnect_370w_firmware:1.3.34:*:*:*:*:*:*:*

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