CVE-2025-66597Network attack vector

Communication decryption via weak web-server cryptography

Published Feb 9, 2026 · Updated Feb 9, 2026

Weak cryptography in the FAST/TOOLS web server R9.01 through R10.04 allows remote attackers to decrypt protected communications. The web server permits broken or risky cryptographic algorithms during connection negotiation, but Yokogawa has not identified the individual algorithms. An attacker must reach the web service over the network; no privileges or user interaction are required, and the documented effects are disclosure with limited data alteration.

CVSS severity8.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak cryptography in the FAST/TOOLS web server R9.01 through R10.04 allows remote attackers to decrypt protected communications. The web server permits broken or risky cryptographic algorithms during connection negotiation, but Yokogawa has not identified the individual algorithms. An attacker must reach the web service over the network; no privileges or user interaction are required, and the documented effects are disclosure with limited data alteration.

The record

CVE
CVE-2025-66597
Published
Feb 9, 2026
Updated
Feb 9, 2026
Vendor
Yokogawa Electric Corporation
Product
FAST/TOOLS
Classifications
CWE-327, T1040
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=R9.01 <=R10.04

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yokogawa Electric Corporation · FAST/TOOLSversion=R9.01 <=R10.04

Published CVSS scores

8.2Yokogawa Electric CorporationCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
8.8Yokogawa Electric CorporationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm
T1040Network Sniffing

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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