No exploitation reportedFix available

CVE-2021-20826

No exploitation reported by the sources we read.

Published2021-12-24
WeaknessCWE-522

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2021-12-2407:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-20826?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-20826?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Idec data file manager

Branch	Affected	Fixed in	Source
2.12	≤ 2.12.1	no fix published	NVD

Idec microsmart fc6a firmwareversion to verify

Branch	Affected	Fixed in	Source
2.32	≤ 2.32	no fix published	NVD

Idec microsmart plus fc6a firmwareversion to verify

Branch	Affected	Fixed in	Source
1.91	≤ 1.91	no fix published	NVD

2 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-22-006-03 CISA9 known affected
IDEC PLCs
Data File Manager: v2.12.1 and earlier · FC6A MICROSmart All-in-One CPU Module: v2.32 and earlier · FC6A MICROSmart Plus CPU Module: v1.91 and earlier · +6 more

Full record on NVD

Fix

Vendor fix CISA ICSA-22-006-03 · 9 productsWindLDR: v8.20.0 and later
Mitigation from the vendor CISA ICSA-22-006-03 · 9 productsFC6A MICROSmart All-in-One CPU Module: v2.40 and later
Mitigation from the vendor CISA ICSA-22-006-03 · 9 productsFC6B MICROSmart All-in-One CPU Module: v2.40 and later
Mitigation from the vendor CISA ICSA-22-006-03 · 9 productsFC6A MICROSmart Plus CPU Module: v2.00 and later
Mitigation from the vendor CISA ICSA-22-006-03 · 9 productsFC6B MICROSmart Plus CPU Module: v2.40 and later
Mitigation from the vendor CISA ICSA-22-006-03 · 9 productsFT1A Controller SmartAXIS Pro/Lite: v2.40 and later

Advisories and patches

www.idec.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.6read 2026-10-23
NVDCVSS 2.03.3read 2026-10-23
NVDweakness (CWE)CWE-522read 2026-10-23
FIRST EPSSEPSS score0.4 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
Published: 2021-12-24
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-20826?

Is CVE-2021-20826 actively exploited?

Active exploitation of CVE-2021-20826 has not been confirmed. Its EPSS score was 0.4% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-20826?

CVE-2021-20826 has a CVSS v3 base score of 7.6 (HIGH severity), with vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L.

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