CVE-2025-66597VulnerabilityPublished 9 Feb 2026

CVE-2025-66597: Yokogawa Electric FAST/TOOLS · Weak Cryptography

Affects Yokogawa Electric FAST/TOOLSSource CVE Database V5

Not known to be exploited · CVSS 8.8 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

8.8High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Yokogawa Electric CorporationFAST/TOOLS	Affected ≥ R9.01, ≤ R10.04	Fixed in–

AI-suggested

1. Monitor Yokogawa Electric Corporation communications for official patches or updates addressing CVE-2025-66597 and apply them promptly once available. 2. Until patches are released, implement network segmentation to isolate FAST/TOOLS servers from untrusted networks and limit access strictly to authorized personnel and systems. 3. Deploy VPNs or TLS tunnels with strong, modern cryptographic algorithms to encapsulate communications to and from FAST/TOOLS web servers, mitigating the weak native cryptography. 4. Conduct thorough network traffic monitoring and anomaly detection to identify unusual access patterns or data exfiltration attempts targeting FAST/TOOLS components. 5. Review and harden firewall rules to restrict inbound and outbound traffic related to FAST/TOOLS to known and trusted IP addresses. 6. Educate operational technology (OT) and IT security teams about this vulnerability to ensure rapid detection and response. 7. Consider deploying intrusion detection/prevention systems (IDS/IPS) tuned to detect exploitation attempts against this vulnerability. 8. Maintain up-to-date asset inventories to quickly identify all FAST/TOOLS instances and assess exposure.

Description

CVE-2025-66597 is a high-severity vulnerability in Yokogawa Electric Corporation's FAST/TOOLS software versions R9.01 to R10.04. The issue arises from the use of weak cryptographic algorithms, which can allow attackers to decrypt communications between clients and the web server. This vulnerability requires no authentication or user interaction and can be exploited remotely over the network. While no known exploits are currently in the wild, the weakness poses a significant risk to confidentiality and potentially integrity of data transmitted. European organizations using FAST/TOOLS in critical industrial control or monitoring environments could face data exposure or interception risks. Mitigation involves upgrading to patched versions once available or applying compensating controls such as network segmentation and encrypted tunnels. Countries with significant industrial automation sectors and Yokogawa customer bases, such as Germany, France, Italy, and the UK, are most likely to be affected. Due to the critical nature of industrial control systems, this vulnerability demands prompt attention to prevent potential espionage or sabotage.

Impact

For European organizations, especially those in critical infrastructure sectors such as energy, manufacturing, and utilities, this vulnerability could lead to unauthorized disclosure of sensitive operational data. Attackers decrypting communications could gain insights into industrial processes, potentially enabling sabotage or competitive espionage. The confidentiality breach could also expose credentials or configuration details, facilitating further attacks. Although integrity and availability impacts are rated lower, the exposure of sensitive data alone can have severe regulatory and operational consequences under GDPR and NIS Directive frameworks. The risk is heightened for organizations using FAST/TOOLS in network environments accessible from less secure or public networks. The potential for remote exploitation without authentication increases the attack surface, making European industrial operators prime targets. This vulnerability could undermine trust in industrial automation systems and lead to costly incident response and remediation efforts.

Summary

CVE-2025-66597 identifies a cryptographic weakness in Yokogawa Electric Corporation's FAST/TOOLS software suite, specifically versions R9.01 through R10.04, which includes packages RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB. The vulnerability stems from the use of broken or risky cryptographic algorithms (CWE-327) to secure communications between the web server and clients. These weak algorithms can be exploited by attackers to decrypt intercepted network traffic, potentially exposing sensitive operational data or credentials. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The CVSS 4.0 score of 8.8 reflects high severity, with network attack vector, low attack complexity, and no privileges or user interaction needed. The impact on confidentiality is high, with limited impact on integrity and availability. Although no exploits have been reported in the wild yet, the vulnerability poses a significant threat to industrial control systems that rely on FAST/TOOLS for monitoring and control. The lack of available patches at the time of publication necessitates immediate risk mitigation through alternative controls. Given the critical role of FAST/TOOLS in industrial environments, exploitation could lead to data leakage, espionage, or disruption of industrial processes.

CWE-327Use of a Broken or Risky Cryptographic Algorithm (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses a broken or risky cryptographic algorithm or protocol.
Architecture and Design · Libraries or Frameworks
When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations.
Architecture and Design
Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms.
Architecture and Design
Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
OWASP Cheat Sheets
Cryptographic Storage (opens in a new tab)
Key Management (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.7 (opens in a new tab)
V2.9.3 (opens in a new tab)
V6.2.2 (opens in a new tab)
Attack patterns
Encryption Brute Forcing (opens in a new tab)
Creating a Rogue Certification Authority Certificate (opens in a new tab)
Signature Spoof (opens in a new tab)
Signature Spoofing by Improper Validation (opens in a new tab)
Cryptanalysis of Cellular Encryption (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

web-material3.yokogawa.com/1/39206/files/YSAR-26-0001-E.pdf (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Feb 2026, 13:18 UTC

WeaknessesCWE-327

Technical details

References

Community reviews

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