CyberSecBulletin
CVE-2026-1874NVD status: Analyzed

MELSEC iQ-F Series FX5-ENET/IP Ethernet Module…: Always-Incorrect Control Flow Implementation

Published Updated By the CyberSecBulletin desk

CVE-2026-1874 is a high-severity always-incorrect control flow implementation vulnerability in MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP from Mitsubishi Electric, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP versions: versions 1.106 and prior. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on mitsubishielectric.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Mitsubishi ElectricMELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IPversions 1.106 and priorNot stated
Mitsubishi ElectricMELSEC iQ-F Series FX5-EIP EtherNet/IP Module FX5-EIPversions 1.000 and priorNot stated
Mitsubishi ElectricMelsec Iq-f Fx5-eip Firmware1.000 and earlierNot stated
Mitsubishi ElectricMelsec Iq-f Fx5-enet/ip Firmware1.106 and earlierNot stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.08.7HighCNA (yd.MitsubishiElectric.co.jp)
CVSS 3.17.5HighNVD

Official description

Always-Incorrect Control Flow Implementation vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP versions 1.106 and prior and Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-EIP EtherNet/IP Module FX5-EIP versions 1.000 and prior allows a remote attacker to cause a denial-of-service (DoS) condition on the products by continuously sending UDP packets to the products. A system reset of the product is required for recovery.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Always-Incorrect Control Flow Implementation

The code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated.

More Always-Incorrect Control Flow Implementation vulnerabilities (CWE-670)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP

All MELSEC iQ-F Series FX5-ENET/IP Ethernet Module FX5-ENET/IP vulnerabilities

Recent Always-Incorrect Control Flow Implementation vulnerabilities

Spotted an error? Tell us.