CVE-2021-32976Network attack vector

Remote code execution via web-server stack overflow

Published Apr 1, 2022 · Updated Apr 16, 2025

Stack-based buffer overflow in Moxa NPort IAW5000A-I/O Series firmware 2.2 and earlier allows remote attackers to execute code via its built-in web server. The server copies attacker-controlled input into stack buffers without adequate bounds checking, allowing memory corruption across five overflow paths. No authentication or user interaction is required, and exploitation can instead interrupt service through denial of service.

CVSS severity9.8
Critical
EPSS probability2.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Moxa NPort IAW5000A-I/O Series firmware 2.2 and earlier allows remote attackers to execute code via its built-in web server. The server copies attacker-controlled input into stack buffers without adequate bounds checking, allowing memory corruption across five overflow paths. No authentication or user interaction is required, and exploitation can instead interrupt service through denial of service.

The record

CVE
CVE-2021-32976
Published
Apr 1, 2022
Updated
Apr 16, 2025
Vendor
Moxa
Product
NPort IAW5000A-I/O Series
Classifications
CWE-121, CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 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=unspecified <=2.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Moxa · NPort IAW5000A-I/O Seriesversion=unspecified <=2.2

Published CVSS scores

9.8ICS-CERT CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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