CVE-2025-66598
Published: 09 February 2026
Summary
CVE-2025-66598 is a high-severity Use of a Broken or Risky Cryptographic Algorithm (CWE-327) vulnerability in Yokogawa Fast\/Tools. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 5.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Contacts with security groups provide timely information on broken or risky cryptographic algorithms, reducing the likelihood of their selection and use.
Ongoing education and sharing of recommended practices helps organizations identify and migrate away from broken or risky cryptographic algorithms.
Cross-organization threat feeds commonly include advances in cryptanalysis and active exploits against weak or broken algorithms, allowing organizations to deprecate them proactively.
Capital planning and funding allow selection and ongoing support of strong cryptographic algorithms rather than weak or broken ones.
Risk updates surface newly-broken or risky cryptographic algorithms as threat intelligence and computing advances evolve, enabling timely replacement.
Scanners flag use of broken or weak cryptographic algorithms via known-vulnerability databases.
Enforces approved cryptographic algorithms for each use case, blocking use of broken or risky algorithms.
Flaw remediation replaces broken or risky cryptographic algorithms once safer implementations are released by vendors.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Outdated/weak TLS directly enables passive or active decryption of web traffic, facilitating Adversary-in-the-Middle attacks.
NVD Description
A vulnerability has been found in FAST/TOOLS provided by Yokogawa Electric Corporation. This product supports old SSL/TLS versions, potentially allowing an attacker to decrypt communications with the web server. The affected products and versions are as follows: FAST/TOOLS (Packages: RVSVRN,…
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UNSVRN, HMIWEB, FTEES, HMIMOB) R9.01 to R10.04
Deeper analysisAI
CVE-2025-66598 is a vulnerability in Yokogawa Electric Corporation's FAST/TOOLS software that supports outdated SSL/TLS versions, potentially enabling attackers to decrypt communications with the web server. The issue, classified under CWE-327 (Broken or Risky Cryptographic Algorithm), affects FAST/TOOLS packages including RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB in versions R9.01 through R10.04. It has a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N), indicating high severity due to significant confidentiality impact.
The vulnerability can be exploited remotely over the network by unauthenticated attackers with low complexity and no user interaction required. Successful exploitation allows attackers to decrypt sensitive communications between clients and the FAST/TOOLS web server, potentially exposing confidential data transmitted over these connections.
Mitigation details are provided in the vendor advisory YSAR-26-0001-E, available at https://web-material3.yokogawa.com/1/39206/files/YSAR-26-0001-E.pdf. Security practitioners should consult this document for patching instructions and recommended workarounds.
Details
- CWE(s)