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Fencer Vulns
medium 6.5

CVE-2021-21967 json

An out-of-bounds write vulnerability exists in the OTA update task functionality of Sealevel Systems, Inc.

published 2022-04-14 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-9138

cvss
6.5
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 55%
public exploits
0
none known

Summary

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.

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.74% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • talosintelligence.com https://talosintelligence.com/vulnerability_reports/TALOS-2021-1394 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 6.5 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C

Affected products

  • Sealevel Systems, Inc. SeaConnect 370W

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.