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TI-2021-05004 Aliases CVE-2021-21959GHSA-86q7-w6v5-827g

Improper certificate validation in Sealevel

Priority HIGH 68CWE-295Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Spoofing
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-295.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00843 58th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
—SealevelSealevel Systems, Inc. SeaConnect 370W v1.3.34—No fix listedCNA
  • Sealevel Vendor— Affected Sealevel Systems, Inc. SeaConnect 370W v1.3.34 Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPEVersionsRoleVendor
cpe:2.3:o:sealevel:seaconnect_370w_firmware:1.3.34:*:*:*:*:*:*:*1.3.34VulnerableSealevel
cpe:2.3:h:sealevel:seaconnect_370w:-:*:*:*:*:*:*:*not specified by NVDRunning onSealevel
  • cpe:2.3:o:sealevel:seaconnect_370w_firmware:1.3.34:*:*:*:*:*:*:* Versions 1.3.34 Vulnerable ·Sealevel
  • cpe:2.3:h:sealevel:seaconnect_370w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Sealevel

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-21959
  2. 2026-10-03 Alias added: GHSA-86q7-w6v5-827g

References

Exploit 1

  • TI-2021-05006 Stack-based buffer overflow in Sealevel CVSS 3.1CRITICAL 10.0
  • TI-2021-05005 Stack-based buffer overflow in Sealevel CVSS 3.1CRITICAL 10.0
  • TI-2021-05010 Improper access control in Sealevel CVSS 3.1CRITICAL 9.3
  • TI-2021-05009 Improper access control in Sealevel CVSS 3.1HIGH 7.4
  • TI-2021-05013 Improper input validation in Sealevel CVSS 3.1HIGH 8.3
  • TI-2021-05007 Heap-based buffer overflow in Sealevel CVSS 3.1HIGH 8.1
See all 11 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences