How severe is CVE-2021-40390?

CVE-2021-40390 has a CVSS 3.x base score of 9.8, 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-2021-40390 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40390?

CVE-2021-40390 affects Moxa Mxview. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40390?

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-2021-40390 published?

CVE-2021-40390 was published on 2022-04-14 and last updated on 2026-06-17.

CVE-2021-40390

CVE-2021-40390 is a critical-severity vulnerability in Moxa Mxview with a CVSS 3.x base score of 9.8. 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-798.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (82nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-798
Affected product: Moxa Mxview
Published: 2022-04-14
Last modified: 2026-06-17

Description

An authentication bypass vulnerability exists in the Web Application functionality of Moxa MXView Series 3.2.4. A specially-crafted HTTP request can lead to unauthorized access. An attacker can send an HTTP request to trigger this vulnerability.

Frequently asked questions

What is CVE-2021-40390?: An authentication bypass vulnerability exists in the Web Application functionality of Moxa MXView Series 3.2.4. A specially-crafted HTTP request can lead to unauthorized access. An attacker can send an HTTP request to trigger this vulnerability.
How severe is CVE-2021-40390?: CVE-2021-40390 has a CVSS 3.x base score of 9.8, 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-2021-40390 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (82nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40390?: CVE-2021-40390 affects Moxa Mxview. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40390?: 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-2021-40390 published?: CVE-2021-40390 was published on 2022-04-14 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1401

Affected products (1)

cpe:2.3:a:moxa:mxview:3.2.4:*:*:*:*:*:*:*

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