How severe is CVE-2021-21961?

CVE-2021-21961 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21961 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21961?

CVE-2021-21961 affects Sealevel Seaconnect 370w Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-21961?

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

When was CVE-2021-21961 published?

CVE-2021-21961 was published on 2022-02-04 and last updated on 2026-06-17.

CVE-2021-21961

CVE-2021-21961 is a critical-severity vulnerability in Sealevel Seaconnect 370w Firmware with a CVSS 3.x base score of 10.0. 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
CVSS v2: 7.5
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Sealevel Seaconnect 370w Firmware
Published: 2022-02-04
Last modified: 2026-06-17

Description

A stack-based buffer overflow vulnerability exists in the NBNS functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. A specially-crafted network packet can lead to remote code execution. An attacker can send a malicious packet to trigger this vulnerability.

Frequently asked questions

What is CVE-2021-21961?: A stack-based buffer overflow vulnerability exists in the NBNS functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. A specially-crafted network packet can lead to remote code execution. An attacker can send a malicious packet to trigger this vulnerability.
How severe is CVE-2021-21961?: CVE-2021-21961 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21961 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21961?: CVE-2021-21961 affects Sealevel Seaconnect 370w Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-21961?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21961 published?: CVE-2021-21961 was published on 2022-02-04 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1389

Affected products (1)

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

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