CVE-2021-21967

highpriority · track · 24EPSS 0.007 · 55 %ileEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.74% (55th) EPSS

CVSS 7.1 · high

Is it mine?

2 products

Check your exposure

Who says so?

3 sources

cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-27

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.

cvss

Technical severity, 0–10. One row per scoring source.

7.1

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.4–7.1

v2.07.1highAV:N/AC:M/Au:N/C:N/I:N/A:Cprimary · NVD / NIST USexploitability 8.6 · impact 6.9

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.2 · impact 3.6

v3.06.5mediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Hsecondary · ENISA EU

v3.06.5mediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:Hsecondary · talos-cna@cisco.com USexploitability 2.2 · impact 4.2

v3.15.4mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-120USprimary

affected products (2)

Products and version ranges known to be affected.

Sealevel Systems, Inc. SeaConnect 370W≤ v1.3.34enisa_euvdEU
sealevel seaconnect 370w firmware= 1.3.34nvdUScpe:2.3:o:sealevel:seaconnect_370w_firmware:*:*:*:*:*:*:*:*

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd NVD CVE.org MITRE

published 2022-04-14modified 2026-06-17

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+5663 more

references (5)

External citations — patches, advisories, analysis.

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