Mitsubishi Electric MELSEC-F Series (CVE-2021-20613)

high Tenable OT Security Plugin ID 501189


The remote OT asset is affected by a vulnerability.


Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.

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The following text was originally created by the Cybersecurity and Infrastructure Security Agency (CISA). The original can be found at

Mitsubishi Electric corrected this vulnerability in the following products and versions, as follows:

- FX3U-ENET: Firmware Version 1.17 or later
- FX3U-ENET-L: Firmware Version 1.17 or later
- FX3U-ENET-P502: Firmware Version 1.17 or later

Mitsubishi Electric also recommends users take the following mitigation measures to minimize the risk of exploiting this vulnerability:

- Use a firewall, VPN, or other barrier to prevent unauthorized access when Internet access is required.
- Use within a LAN and block access from untrusted networks and hosts through firewalls.

For specific update instructions and additional details see the Mitsubishi Electric advisory.

See Also

Plugin Details

Severity: High

ID: 501189

Version: 1.3

Type: remote

Family: Tenable.ot

Published: 6/12/2023

Updated: 11/6/2023

Risk Information


Risk Factor: Low

Score: 3.6


Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2021-20613


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:mitsubishielectric:fx3u-enet-l_firmware, cpe:/o:mitsubishielectric:fx3u-enet-p502_firmware, cpe:/o:mitsubishielectric:fx3u-enet_firmware

Required KB Items: Tenable.ot/Mitsubishi

Exploit Ease: No known exploits are available

Patch Publication Date: 1/14/2022

Vulnerability Publication Date: 1/14/2022

Reference Information

CVE: CVE-2021-20613

CWE: 665