Security readout for executives and security teams
Plain-English summary
Mitsubishi MELSEC iQ-F Ethernet modules can be forced into a denial-of-service state by a remote attacker sending continuous UDP traffic. Recovery requires a product reset, which may interrupt industrial operations using these modules. The issue is high severity because it is network-reachable and needs no authentication or user interaction.
Executive priority
Prioritize assessment in environments where affected modules support production, safety-adjacent operations, or critical automation. Treat this as an availability risk: exploitation may stop communications and require reset-based recovery. No active exploitation is confirmed in the supplied sources.
Technical view
CVE-2026-1874 is a CWE-670 control-flow flaw affecting FX5-ENET/IP versions 1.106 and prior and FX5-EIP versions 1.000 and prior. CVSS v4.0 is 8.7. The vulnerability allows unauthenticated network attackers to impact availability by continuously sending UDP packets, causing a DoS condition requiring reset.
Likely exposure
Exposure is limited to Mitsubishi MELSEC iQ-F Series FX5-ENET/IP and FX5-EIP modules at the affected versions. Risk is greatest where these modules are reachable from untrusted networks or poorly segmented plant networks carrying UDP traffic.
Exploitation context
The provided sources describe remote unauthenticated DoS via continuous UDP packets. The CVE is not listed as CISA KEV in the supplied data, and no cited source states active exploitation. The main operational concern is forced downtime and manual recovery through reset.
Researcher notes
The public description does not provide packet specifics, affected ports, or root-cause detail beyond CWE-670 and continuous UDP traffic. Avoid assuming broader MELSEC products are affected. Validate only the two named module families and versions unless vendor guidance expands scope.
Mitigation direction
- Identify deployed FX5-ENET/IP and FX5-EIP modules and firmware versions.
- Review Mitsubishi Electric, JVN, and CISA advisories for official updates or mitigations.
- Restrict network access to affected modules from untrusted or unnecessary hosts.
- Use industrial network segmentation and monitoring for abnormal UDP traffic.
- Prepare operational procedures for safe reset and recovery if disruption occurs.
Validation and detection
- Confirm whether affected module models are present in asset inventory.
- Verify firmware versions against FX5-ENET/IP 1.106 and FX5-EIP 1.000 thresholds.
- Check network paths that can send UDP traffic to these modules.
- Review logs or monitoring for unusual sustained UDP traffic patterns.
- Document reset dependencies and business processes impacted by module downtime.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-670: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-1874 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.mitsubishielectric.com/psirt/vulnerability/pdf/2025-021_en.pdfCVE reference · vendor-advisory
- https://jvn.jp/vu/JVNVU93286687/CVE reference · government-resource
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-62-01CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Always-Incorrect Control Flow Implementation
Always-Incorrect Control Flow Implementation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.