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PatchSiren cyber security CVE debrief

CVE-2025-66594 Yokogawa CVE debrief

CVE-2025-66594 is a medium-severity information disclosure issue in Yokogawa FAST/TOOLS. The advisory says detailed messages are shown on an error page, and that exposed information could be used in other attacks. CISA lists the issue as network exploitable with low confidentiality impact and no integrity or availability impact in the supplied CVSS vector.

Vendor
Yokogawa
Product
FAST/TOOLS
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-02-10
Original CVE updated
2026-02-10
Advisory published
2026-02-10
Advisory updated
2026-02-10

Who should care

OT/ICS operators, plant security teams, and administrators responsible for Yokogawa FAST/TOOLS deployments should prioritize this advisory, especially where the system is reachable from internal or external networks or where error pages may be exposed to users.

Technical summary

The supplied advisory describes an information exposure condition in FAST/TOOLS error handling. The published CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N, which corresponds to a score of 5.3 (Medium). Yokogawa recommends updating to revision R10.04, applying patch software CS_e12787, and then applying R10.04 SP3. The advisory also recommends broader security controls such as patching, antivirus, backup and recovery, zoning, hardening, whitelisting, and firewalls.

Defensive priority

Medium priority for exposure reduction and patch management. The issue does not indicate disruption or direct code execution in the supplied corpus, but it may support follow-on attacks by revealing details that should not be visible.

Recommended defensive actions

  • Upgrade to Yokogawa FAST/TOOLS revision R10.04, apply patch software CS_e12787, and then apply R10.04 SP3.
  • Review externally or internally reachable error pages and ensure detailed messages are not exposed to unauthenticated users.
  • Apply compensating controls recommended by Yokogawa and CISA, including zoning, hardening, whitelisting, and firewall restrictions.
  • Validate backups and recovery procedures before maintenance windows.
  • Use the official Yokogawa contact path for clarification or deployment questions if needed.

Evidence notes

Based only on the supplied CISA CSAF advisory ICSA-26-041-01 for CVE-2025-66594. The advisory states: "Detailed messages are displayed on the error page. This information could be exploited by an attacker for other attacks." The supplied CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (5.3 Medium). Remediation in the source corpus is to update to R10.04, apply patch software CS_e12787, and then apply R10.04 SP3. No KEV listing is present in the supplied data.

Official resources

Publicly disclosed in CISA advisory ICSA-26-041-01 on 2026-02-10; the supplied data indicates no KEV listing and no known ransomware campaign use.