CVE-2021-21965Public exploitNetwork attack vector

Unauthenticated device reboot via SeaMAX request

Published Feb 4, 2022 · Updated Apr 15, 2025

Improper access control in SeaConnect 370W 1.3.34 allows remote attackers to reboot the device through the SeaMAX Ethernet API. The UDP 30718 request dispatcher accepts an unauthenticated four-byte Write Setup Record 3 packet and invokes Reboot when its first byte is zero. When the optional SeaMAX Ethernet API is enabled, repeated packets can keep the industrial I/O module unusable after each network reconnection.

CVSS severity8.6
High
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in SeaConnect 370W 1.3.34 allows remote attackers to reboot the device through the SeaMAX Ethernet API. The UDP 30718 request dispatcher accepts an unauthenticated four-byte Write Setup Record 3 packet and invokes Reboot when its first byte is zero. When the optional SeaMAX Ethernet API is enabled, repeated packets can keep the industrial I/O module unusable after each network reconnection.

The record

CVE
CVE-2021-21965
Published
Feb 4, 2022
Updated
Apr 15, 2025
Vendor
Sealevel Systems, Inc.
Product
SeaConnect 370W
Classifications
CWE-284, CWE-287, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Sealevel Systems, Inc. SeaConnect 370W v1.3.34

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Sealevel Systems, Inc. · SeaConnect 370Wversion=Sealevel Systems, Inc. SeaConnect 370W v1.3.34

Published CVSS scores

9.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H
6.4NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:P
8.6Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
CWE-287Improper Authentication
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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