CVE-2025-66599VulnerabilityPublished 9 Feb 2026

CVE-2025-66599: Yokogawa Electric FAST/TOOLS · CWE-497

Affects Yokogawa Electric FAST/TOOLSSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 22% 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:L/VI:N/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: Low
Vulnerable system integrity: None
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within 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

Since no official patches are currently available, European organizations should implement compensating controls to mitigate this vulnerability. First, restrict external access to FAST/TOOLS web interfaces by enforcing network segmentation and firewall rules to limit exposure to trusted internal networks only. Employ web application firewalls (WAFs) to detect and block suspicious requests that might exploit information disclosure. Review and harden web server configurations to prevent leakage of directory paths, such as disabling detailed error messages and directory listings. Conduct thorough security audits and penetration testing focused on the affected FAST/TOOLS components to identify and remediate other potential weaknesses. Monitor network traffic and logs for unusual access patterns or reconnaissance activity targeting these systems. Engage with Yokogawa support channels to obtain updates or patches as they become available, and plan for timely deployment. Additionally, implement strict access controls and multi-factor authentication for administrative interfaces to reduce risk from lateral movement if reconnaissance leads to further exploitation.

Description

CVE-2025-66599 is a medium-severity vulnerability in Yokogawa Electric Corporation's FAST/TOOLS software versions R9.01 through R10.04. The flaw involves the unintended disclosure of physical file system paths on web pages served by the affected products. This information disclosure can aid attackers in crafting further targeted attacks by revealing internal directory structures. The vulnerability requires no authentication or user interaction and can be exploited remotely over the network. Although no known exploits are currently in the wild, the exposure of sensitive path information can facilitate reconnaissance and subsequent exploitation steps. The affected FAST/TOOLS packages include RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB. European organizations using these versions in critical industrial control or monitoring environments should prioritize mitigation to reduce attack surface. No official patches have been linked yet, so compensating controls are recommended.

Impact

For European organizations, especially those operating critical infrastructure or industrial automation environments, this vulnerability poses a moderate risk. Disclosure of physical paths can facilitate reconnaissance by threat actors, enabling them to map the internal system architecture and identify potential attack vectors. This is particularly concerning for sectors such as energy, manufacturing, utilities, and transportation, where Yokogawa's FAST/TOOLS is commonly deployed. Attackers could use the disclosed information to craft targeted exploits, potentially leading to unauthorized access, data exfiltration, or disruption of industrial processes. Although the vulnerability itself does not allow direct system compromise, it lowers the barrier for more severe attacks. Given the strategic importance of industrial control systems in Europe and the increasing targeting of such environments by cyber adversaries, the impact could extend to operational downtime, safety risks, and economic losses. The lack of authentication and user interaction requirements increases the ease of exploitation, raising the urgency for mitigation in European contexts.

CWE-497Exposure of Sensitive System Information to an Unauthorized Control Sphere (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product does not properly prevent sensitive system-level information from being accessed by unauthorized actors who do not have the same level of access to the underlying system as the product does.
Architecture and Design · Implementation
Production applications should never use methods that generate internal details such as stack traces and error messages unless that information is directly committed to a log that is not viewable by the end user.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V14.3.2 (opens in a new tab)
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
Attack patterns
Web Application Fingerprinting (opens in a new tab)
System Location Discovery (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, 13:19 UTC

WeaknessesCWE-497

Technical details

References

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