How severe is CVE-2021-33823?

CVE-2021-33823 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-33823 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33823?

CVE-2021-33823 affects Moxa Mgate Mb3180 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33823?

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

When was CVE-2021-33823 published?

CVE-2021-33823 was published on 2021-06-18 and last updated on 2026-06-17.

CVE-2021-33823

CVE-2021-33823 is a high-severity vulnerability in Moxa Mgate Mb3180 Firmware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Moxa Mgate Mb3180 Firmware
Published: 2021-06-18
Last modified: 2026-06-17

Description

An issue was discovered on MOXA Mgate MB3180 Version 2.1 Build 18113012. Attacker could send a huge amount of TCP SYN packet to make web service's resource exhausted. Then the web server is denial-of-service.

Frequently asked questions

What is CVE-2021-33823?: An issue was discovered on MOXA Mgate MB3180 Version 2.1 Build 18113012. Attacker could send a huge amount of TCP SYN packet to make web service's resource exhausted. Then the web server is denial-of-service.
How severe is CVE-2021-33823?: CVE-2021-33823 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-33823 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33823?: CVE-2021-33823 affects Moxa Mgate Mb3180 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33823?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33823 published?: CVE-2021-33823 was published on 2021-06-18 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:moxa:mgate_mb3180_firmware:2.1:build_18113012:*:*:*:*:*:*

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