What is the CVSS score of CVE-2025-66606?

CVE-2025-66606 has a CVSS 3.1 base score of 9.6 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2025-66606?

Within 24 hours: Identify all systems running FAST/TOOLS and isolate them from untrusted networks; notify Yokogawa for patch availability and timeline. Within 7 days: Implement network segmentation to restrict access to FAST/TOOLS; deploy WAF rules to filter malicious URL-encoded payloads; enable enhanced logging and monitoring. Within 30 days: Evaluate alternative control systems; establish vendor communication cadence for patch release; conduct penetration testing once mitigations are in place.

Fast Tools CVE-2025-66606

CRITICAL

Improper Neutralization of Invalid Characters in Identifiers in Web Pages (CWE-86)

2026-02-09 7168b535-132a-4efe-a076-338f829b2eb9

Information Disclosure Fast Tools Yokogawa

9.6

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-86 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Invalid character neutralization
Impact	CVSS 9.6 — three critical vulnerabilities in the same SCADA platform.
Exploit ScenarioDerived	An attacker exploits the encoding flaw to inject malicious content into the SCADA web interface.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Yokogawa FAST/TOOLS has a third vulnerability involving improper encoding of output that could enable injection attacks against the SCADA web interface.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 9.6

Output encoding flaw in Yokogawa FAST/TOOLS enables injection attacks.

RemediationAI

Apply all Yokogawa FAST/TOOLS patches.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-86 improper neutralization of invalid characters in identifiers in Yokogawa FAST/TOOLS, the third vulnerability in the advisory.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.6 CRITICAL

AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

A vulnerability has been found in FAST/TOOLS provided by Yokogawa Electric Corporation.

This product does not properly encode URLs. An attacker could tamper with web pages or execute malicious scripts.

The affected products and versions are as follows: FAST/TOOLS (Packages: RVSVRN, UNSVRN, HMIWEB, FTEES, HMIMOB) R9.01 to R10.04

Executive ViewAI

Why It Matters

A critical vulnerability (CVE-2025-66606) in Yokogawa FAST/TOOLS allows attackers to exploit improper URL encoding, potentially enabling unauthorized access, data theft, or system compromise. Organizations using this industrial control software face immediate risk as no vendor patch is currently available, requiring urgent interim protective measures.

Business Impact: Severe

Compensating Controls

Implement Web Application Firewall (WAF) rules to block malformed URL-encoded requests; enforce network segmentation restricting FAST/TOOLS access to authorized administrators only via VPN/jumphost; disable non-essential features and input fields; enforce strict input validation at application entry points; enable comprehensive logging for forensic analysis; consider temporary operational workarounds or failover to manual processes until patch availability.

Threat Intelligence Overview

EPSS Score

0.0%

Top 86% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +48

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.