VulnerabilityPublished 9 Feb 2026

CVE-2025-66596: Yokogawa Electric FAST/TOOLS · Open Redirect

Affects Yokogawa Electric FAST/TOOLSSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% 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:N/VI:L/VA:N/SC:N/SI:L/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: Low
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: None: There is no loss of confidentiality within the Vulnerable System.
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: 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 Subsequent 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 26 Oct 2026.

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 or the CVSS exploit maturity 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

Implement strict validation of the Host header on all FAST/TOOLS web interfaces to ensure only legitimate, expected hostnames are accepted.
Monitor and filter incoming HTTP requests at the network perimeter to detect and block suspicious or malformed Host headers.
Apply vendor-provided patches or updates as soon as they become available; maintain close communication with Yokogawa for security advisories.
Employ web application firewalls (WAFs) configured to detect and prevent open redirect attempts targeting FAST/TOOLS URLs.
Conduct user awareness training focused on recognizing suspicious URLs and phishing attempts that may exploit this vulnerability.
Review and restrict external access to FAST/TOOLS management interfaces, limiting exposure to trusted networks or VPNs.
Implement logging and alerting for unusual redirect activities to enable rapid detection and response.
Regularly audit and update security policies related to industrial control system web portals to incorporate this vulnerability context.

Description

CVE-2025-66596 is an open redirect vulnerability in Yokogawa Electric Corporation's FAST/TOOLS software versions R9.01 through R10.04. The product fails to properly validate the Host header in HTTP requests, allowing attackers to craft malicious URLs that redirect users to untrusted, potentially harmful websites without user interaction or authentication. This vulnerability has a CVSS 4.0 score of 6.9, indicating medium severity. While no known exploits are currently reported in the wild, exploitation could facilitate phishing or social engineering attacks by leveraging trusted FAST/TOOLS URLs. European organizations using FAST/TOOLS in critical industrial control systems could face reputational damage and increased risk of secondary attacks. Mitigation requires strict validation of Host headers, applying vendor patches when available, and monitoring for suspicious redirects.

Impact

For European organizations, especially those operating critical infrastructure and industrial control systems, this vulnerability poses a significant risk. FAST/TOOLS is a SCADA and industrial automation platform used in sectors such as energy, manufacturing, and utilities. An attacker exploiting this vulnerability could redirect legitimate users to malicious websites designed to harvest credentials, deliver malware, or conduct further social engineering attacks. This could lead to compromised user accounts, unauthorized access to sensitive operational data, or disruption of industrial processes. The indirect impact includes reputational damage, regulatory non-compliance (e.g., under NIS2 Directive), and potential financial losses due to operational downtime or incident response costs. Since exploitation requires no authentication or user interaction, the threat is more accessible to remote attackers, increasing the likelihood of targeted phishing campaigns leveraging trusted FAST/TOOLS URLs. The medium severity rating reflects moderate risk but given the critical nature of affected systems, the impact could be amplified in practice.

CWE-601URL Redirection to Untrusted Site ('Open Redirect') (opens in a new tab)
Base weaknessLikelihood of exploit: LowOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design
Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.
Architecture and Design · Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
OWASP Cheat Sheets
Mass Assignment (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V5.1.5 (opens in a new tab)
Attack patterns
Cross-Site Flashing (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-601

Technical details

References

Community reviews

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