CVE-2021-22800Network attack vector

Unauthenticated service interruption via crafted TCP packet

Published Feb 11, 2022 · Updated Aug 3, 2024

Improper input validation in Schneider Electric Modicon M218 Logic Controller 5.1.0.6 and earlier allows remote attackers to interrupt service. The controller mishandles a crafted packet received on TCP port 1105, causing denial of service; the parsing locus and exact failure mode are undisclosed. No authentication or user interaction is required, and the documented consequence is limited to loss of controller availability.

CVSS severity7.5
High
EPSS probability1.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Schneider Electric Modicon M218 Logic Controller 5.1.0.6 and earlier allows remote attackers to interrupt service. The controller mishandles a crafted packet received on TCP port 1105, causing denial of service; the parsing locus and exact failure mode are undisclosed. No authentication or user interaction is required, and the documented consequence is limited to loss of controller availability.

The record

CVE
CVE-2021-22800
Published
Feb 11, 2022
Updated
Aug 3, 2024
Vendor
Distributed Data Systems
Product
Modicon M218 Logic Controller
Classifications
CWE-20, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=Modicon M218 Logic Controller (V5.1.0.6 and prior)

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Distributed Data Systems · Modicon M218 Logic Controllerversion=Modicon M218 Logic Controller (V5.1.0.6 and prior)

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/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 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-20Improper Input Validation
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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