CVE-2021-21963: An information disclosure vulnerability exists in the Web Server functionality of Sealevel Systems, Inc

Routine

MEDIUM 5.9REMOTEMITIGATE

CVE-2021-21963 is a medium-severity flaw (CVSS 5.9) affecting seaconnect 370w firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An information disclosure vulnerability exists in the Web Server functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. A specially-crafted man-in-the-middle attack can lead to a disclosure of sensitive information. An attacker can perform a man-in-the-middle attack to trigger this vulnerability.

Why this priority

Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-311
Published	2022-02-04
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: sealevel

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-02-04 23:15 UTCPublished CVE record published
2026-06-17 03:36 UTCUpdated Record last modified

sealevel seaconnect 370w firmware MITIGATE

Affected: 1.3.34

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.3.34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-21963?

seaconnect 370w firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-21963 being exploited?

CVE-2021-21963 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-21963 affect?

CVE-2021-21963 affects seaconnect 370w firmware. Severity is medium (CVSS 5.9). An information disclosure vulnerability exists in the Web Server functionality of Sealevel Systems, Inc. SeaConnect 370W v1.3.34. A specially-crafted man-in-the-middle attack can lead to a disclosure of sensitive information. An attacker ca

How urgent is CVE-2021-21963?

Priority 36/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-21971 MEDIUM 5.9 MITIGATE An out-of-bounds write vulnerability exists in the URL_decode functionality of Sealevel Systems, Inc
CVE-2021-21970 HIGH 8.1 MITIGATE An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, In
CVE-2021-21969 HIGH 8.1 MITIGATE An out-of-bounds write vulnerability exists in the HandleSeaCloudMessage functionality of Sealevel Systems, In
CVE-2021-21968 HIGH 8.3 MITIGATE A file write vulnerability exists in the OTA update task functionality of Sealevel Systems, Inc
CVE-2021-21967 MEDIUM 5.9 MITIGATE An out-of-bounds write vulnerability exists in the OTA update task functionality of Sealevel Systems, Inc

References

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