CVE-2021-22779Network attack vector

Unauthenticated controller access via Modbus spoofing

Published Jul 14, 2021 · Updated May 29, 2026

Authentication bypass in affected Schneider Electric products allows remote attackers to gain controller read/write access via Modbus spoofing. The controller accepts spoofed Modbus traffic as trusted engineering communication, exposing unauthorized read and write operations. Network access to the targeted controller is sufficient; no authentication or user interaction is required, and control state can be altered.

CVSS severity9.1
Critical
EPSS probability1.02%
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 affected Schneider Electric products allows remote attackers to gain controller read/write access via Modbus spoofing. The controller accepts spoofed Modbus traffic as trusted engineering communication, exposing unauthorized read and write operations. Network access to the targeted controller is sufficient; no authentication or user interaction is required, and control state can be altered.

The record

CVE
CVE-2021-22779
Published
Jul 14, 2021
Updated
May 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-290, T0836
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. May 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
6.4NVDAV:N/AC:L/Au:N/C:P/I:P/A:N
9.8CISACVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T0836Modify Parameter

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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