CVE-2021-20827

Controller hijacking via cleartext web credentials

Published Dec 24, 2021 · Updated Aug 3, 2024

Cleartext password storage in IDEC PLC products allows attackers to steal PLC Web server credentials from project and backup files. WindLDR, WindEDIT Lite, and Data File Manager write those credentials without adequate protection into ZLD files retained on file servers, backup repositories, or SD cards. Access to such a file is required; recovered credentials grant PLC Web server access that permits controller-output manipulation or PLC suspension.

CVSS severity7.6
High
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cleartext password storage in IDEC PLC products allows attackers to steal PLC Web server credentials from project and backup files. WindLDR, WindEDIT Lite, and Data File Manager write those credentials without adequate protection into ZLD files retained on file servers, backup repositories, or SD cards. Access to such a file is required; recovered credentials grant PLC Web server access that permits controller-output manipulation or PLC suspension.

The record

CVE
CVE-2021-20827
Published
Dec 24, 2021
Updated
Aug 3, 2024
Vendor
IDEC Corporation
Product
IDEC PLC
Classifications
CWE-256, CWE-312, T1552.001
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 24, 2021CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=FC6A Series MICROSmart All-in-One CPU module v2.32 and earlier, FC6A Series MICROSmart Plus CPU module v1.91 and earlier, WindLDR v8.19.1 and earlier, WindEDIT Lite v1.3.1 and earlier, and Data File Manager v2.12.1 and earlier

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

IDEC Corporation · IDEC PLCversion=FC6A Series MICROSmart All-in-One CPU module v2.32 and earlier, FC6A Series MICROSmart Plus CPU module v1.91 and earlier, WindLDR v8.19.1 and earlier, WindEDIT Lite v1.3.1 and earlier, and Data File Manager v2.12.1 and earlier

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.6JPCERT/CCCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-256Plaintext Storage of a Password
CWE-312Cleartext Storage of Sensitive Information
T1552.001Unsecured Credentials: Credentials In Files

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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