CVE-2025-66598Network attack vector

Web traffic decryption via obsolete TLS support

Published Feb 9, 2026 · Updated Feb 9, 2026

Outdated TLS support in Yokogawa Electric Corporation FAST/TOOLS R9.01 through R10.04 allows remote authenticated users to decrypt web traffic. The embedded web server accepts obsolete SSL/TLS protocol versions, but Yokogawa has not identified the accepted versions or configuration locus. Exploitation requires network access and low-privileged credentials, exposing web communications without causing a reported service interruption.

CVSS severity7.1
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Outdated TLS support in Yokogawa Electric Corporation FAST/TOOLS R9.01 through R10.04 allows remote authenticated users to decrypt web traffic. The embedded web server accepts obsolete SSL/TLS protocol versions, but Yokogawa has not identified the accepted versions or configuration locus. Exploitation requires network access and low-privileged credentials, exposing web communications without causing a reported service interruption.

The record

CVE
CVE-2025-66598
Published
Feb 9, 2026
Updated
Feb 9, 2026
Vendor
Yokogawa Electric Corporation
Product
FAST/TOOLS
Classifications
CWE-327, T1040
Attack vector
network
Privileges
authenticated

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 privilegesauthenticated

What is affected?

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

Published CVSS scores

7.1Yokogawa Electric CorporationCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
7.1Yokogawa Electric CorporationCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
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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