Traffic interception via missing HSTS header
Published Feb 9, 2026 · Updated Feb 9, 2026
Missing HSTS in the FAST/TOOLS web server R9.01 through R10.04 allows man-in-the-middle attackers to sniff communications. The affected RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB packages serve responses without an HTTP Strict Transport Security policy, permitting an intercepted browser connection to be downgraded to HTTP. Exploitation requires a network position able to intercept or modify traffic; the published impact covers traffic disclosure and limited modification, not service interruption.
Summary
What happened
Missing HSTS in the FAST/TOOLS web server R9.01 through R10.04 allows man-in-the-middle attackers to sniff communications. The affected RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB packages serve responses without an HTTP Strict Transport Security policy, permitting an intercepted browser connection to be downgraded to HTTP. Exploitation requires a network position able to intercept or modify traffic; the published impact covers traffic disclosure and limited modification, not service interruption.
The record
- CVE
- CVE-2025-66600
- Published
- Feb 9, 2026
- Updated
- Feb 9, 2026
- Vendor
- Yokogawa Electric Corporation
- Product
- FAST/TOOLS
- Classifications
- CWE-358, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 9, 2026CVE publishedPublication date reported by the CVE source.
- Feb 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=R9.01 <=R10.04
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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