CVE-2021-20826

Name: CVE-2021-20826
Creator: NVD / NIST
Published: 2021-12-24T07:15:06.51+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.6/10EPSS 0.39%

Last modified Jun 17, 2026

CVE-2021-20826 is a high-severity vulnerability rated 7.6/10 on the CVSS scale. Unprotected transport of credentials vulnerability in IDEC PLCs (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) allows an attacker to obtain the PLC Web server user credentials from the communication between the PLC and the software. As a result, the complete access privileges to the PLC Web server may be obtained, and manipulation of the PLC output and/or suspension of the PLC may be conducted.. EPSS estimates a 0.39% chance of exploitation in the next 30 days.

Description

Unprotected transport of credentials vulnerability in IDEC PLCs (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) allows an attacker to obtain the PLC Web server user credentials from the communication between the PLC and the software. As a result, the complete access privileges to the PLC Web server may be obtained, and manipulation of the PLC output and/or suspension of the PLC may be conducted.

Metrics

CVSS 3.1

7.6/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L

EPSS Probability

0.39%

30.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-522

Affected Software

Vendor	Product	Versions
Idec	Microsmart Fc6a Firmware	<= 2.32
Idec	Microsmart Plus Fc6a Firmware	<= 1.91
Idec	Data File Manager	<= 2.12.1
Idec	Windedit	<= 1.3.1
Idec	Windldr	<= 8.19.1

References

https://jvn.jp/en/vu/JVNVU92279973/index.htmlThird Party Advisory
https://www.idec.com/home/lp/pdf/2021-12-24-PLC.pdfVendor Advisory
https://jvn.jp/en/vu/JVNVU92279973/index.htmlThird Party Advisory
https://www.idec.com/home/lp/pdf/2021-12-24-PLC.pdfVendor Advisory

Timeline

Published: Dec 24, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20826?

How severe is CVE-2021-20826?

CVE-2021-20826 has a CVSS score of 7.6/10 (HIGH severity). The EPSS model estimates a 0.39% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20826?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20826?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST