No exploitation reported

CVE-2021-27458

No exploitation reported by the sources we read.

Published2021-04-19
WeaknessCWE-404

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

If Ethernet communication of the JTEKT Corporation TOYOPUC product series’ (TOYOPUC-PC10 Series: PC10G-CPU TCC-6353: All versions, PC10GE TCC-6464: All versions, PC10P TCC-6372: All versions, PC10P-DP TCC-6726: All versions, PC10P-DP-IO TCC-6752: All versions, PC10B-P TCC-6373: All versions, PC10B TCC-1021: All versions, PC10B-E/C TCU-6521: All versions, PC10E TCC-4737: All versions; TOYOPUC-Plus Series: Plus CPU TCC-6740: All versions, Plus EX TCU-6741: All versions, Plus EX2 TCU-6858: All versions, Plus EFR TCU-6743: All versions, Plus EFR2 TCU-6859: All versions, Plus 2P-EFR TCU-6929: All versions, Plus BUS-EX TCU-6900: All versions; TOYOPUC-PC3J/PC2J Series: FL/ET-T-V2H THU-6289: All versions, 2PORT-EFR THU-6404: All versions) are left in an open state by an attacker, Ethernet communications cannot be established with other devices, depending on the settings of the link parameters.

Timeline

dates in UTC

2021-04-1922:15CVE 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-2021-27458?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-27458?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Jtekt 2port-efr thu-6404 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Jtekt fl\/et-t-v2h thu-6289 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Jtekt pc10b tcc-1021 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

15 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-21-103-03 CISA18 known affected
JTEKT TOYOPUC products
Plus 2P-EFR TCU-6929: All versions · Plus EX2 TCU-6858: All versions · PC10G-CPU TCC-6353: All versions · +15 more

Full record on NVD

Fix

Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsJTEKT Corporation recommends users to use the following workaround:
Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsAccess the link parameter screen of either “Ethernet” or “Ethernet (32Port).”
Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsAccess the Timer setting by clicking on the “Timers” button.
Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsSet “Non-Reception timer” to “Enable” in the “Timers” section.
Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsAfter setting the link parameter, connect a computer and a PLC with a USB cable and write the link parameter.
Mitigation from the vendor CISA ICSA-21-103-03 · 18 productsAfter the writing is completed, perform a reset/start or power-on again.

Detection

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

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
CNAweakness (CWE)CWE-404read 2026-10-23
FIRST EPSSEPSS score1.1 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2021-04-19
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-27458?

Is CVE-2021-27458 actively exploited?

Active exploitation of CVE-2021-27458 has not been confirmed. Its EPSS score was 1.1% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-27458?

CVE-2021-27458 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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