CVE-2021-40390Public exploitNetwork attack vector

Unauthenticated administrator access via hard-coded polling credentials

Published Apr 14, 2022 · Updated Apr 15, 2025

Authentication bypass in Moxa MXview Series 3.2.0 through 3.2.4 allows remote attackers to gain administrator access over HTTP. The default installation exposes an undocumented polling-engine service on port 4430 that accepts the fixed admin:moxa credentials independently of the web administrator password. No prior authentication is required, and successful login grants administrator access to MXview application functions from remote sites.

CVSS severity10.0
Critical
EPSS probability2.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Moxa MXview Series 3.2.0 through 3.2.4 allows remote attackers to gain administrator access over HTTP. The default installation exposes an undocumented polling-engine service on port 4430 that accepts the fixed admin:moxa credentials independently of the web administrator password. No prior authentication is required, and successful login grants administrator access to MXview application functions from remote sites.

The record

CVE
CVE-2021-40390
Published
Apr 14, 2022
Updated
Apr 15, 2025
Vendor
Moxa
Product
MXview Series
Classifications
CWE-798, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 14, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.2.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Moxa · MXview Seriesversion=3.2.4

Published CVSS scores

10.0Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-798Use of Hard-coded Credentials
T1078Valid Accounts

Public exploit references

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Technologies

Your stack

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Your stack

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