CVE-2021-34566Network attack vector

Memory corruption and crash via unchecked packet copy

Published Nov 9, 2022 · Updated May 1, 2025

Classic buffer overflow in WAGO I/O-Check Service FW1 through FW18 Patch 2 allows remote attackers to crash iocheck and write memory. The service copies data from a specially crafted packet containing OS commands without checking that the destination buffer is large enough. No authentication or user interaction is required; exploitation can corrupt process memory and interrupt the service.

CVSS severity9.1
Critical
EPSS probability1.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Classic buffer overflow in WAGO I/O-Check Service FW1 through FW18 Patch 2 allows remote attackers to crash iocheck and write memory. The service copies data from a specially crafted packet containing OS commands without checking that the destination buffer is large enough. No authentication or user interaction is required; exploitation can corrupt process memory and interrupt the service.

The record

CVE
CVE-2021-34566
Published
Nov 9, 2022
Updated
May 1, 2025
Vendor
WAGO
Product
Edge Controller 0752-8303/8000-0002
Classifications
CWE-120, CAPEC-100, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 9, 2022CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=FW1 <=FW18 Patch 2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WAGO · Edge Controller 0752-8303/8000-0002version=FW1 <=FW18 Patch 2
WAGO · PFC200 Controllerversion=FW1 <=FW18 Patch 2
WAGO · Touch Panel 600 Advanced Lineversion=FW1 <=FW18 Patch 2
WAGO · Touch Panel 600 Marine Lineversion=FW1 <=FW18 Patch 2
WAGO · Touch Panel 600 Standard Lineversion=FW1 <=FW18 Patch 2
WAGO · PFC100 Controllerversion=FW1 <=FW18 Patch 2

Published CVSS scores

9.1CERT@VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CAPEC-100Overflow Buffers
T1499Endpoint Denial of Service

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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