CVE-2025-66605 is a vulnerability classified under CWE-359 (Exposure of Private Information Through Browser Caching) affecting Yokogawa Electric Corporation's FAST/TOOLS software packages including RVSVRN, UNSVRN, HMIWEB, FTEES, and HMIMOB versions R9.01 through R10.04. The core of the vulnerability lies in the web interface's input fields having the HTML autocomplete attribute enabled. This attribute causes browsers to store entered data locally to facilitate autofill in future sessions. While convenient, this behavior can inadvertently expose sensitive information if the browser's stored data is accessed by unauthorized users or malware on the client machine. The vulnerability does not require any authentication to exploit but does require user interaction, such as entering data into the affected input fields. The CVSS 4.0 score is 2.1, indicating low severity, with network attack vector, high attack complexity, no privileges required, user interaction needed, and low confidentiality impact. There is no impact on integrity or availability. No patches or fixes have been published at the time of disclosure, and no known exploits have been reported in the wild. This vulnerability primarily risks confidentiality through local data exposure rather than remote compromise or system disruption.

For European organizations, particularly those in critical infrastructure sectors such as energy, manufacturing, and utilities where Yokogawa's FAST/TOOLS is commonly deployed, this vulnerability poses a risk of sensitive operational data being inadvertently stored in user browsers. If an attacker gains access to a user's workstation or browser profile, they could retrieve this cached data, potentially exposing operational parameters or credentials entered into the system. Although the impact on system integrity and availability is negligible, the confidentiality breach could facilitate further targeted attacks or insider threats. The risk is heightened in environments where endpoint security is weak or where shared workstations are used. However, the overall impact is limited by the requirement for user interaction and the need for local access to the browser data. Since no remote exploitation is possible without user involvement, the threat is primarily to endpoint security and data privacy rather than direct system compromise.

European organizations should implement specific mitigations beyond generic advice: 1) Disable the autocomplete attribute on all input fields within FAST/TOOLS web interfaces by configuring or customizing the application if possible, or request this from Yokogawa through support channels. 2) Enforce strict endpoint security policies including browser profile protection, disk encryption, and regular clearing of browser cache and autofill data to minimize risk of local data exposure. 3) Educate users about the risks of storing sensitive information in browser autofill and encourage use of dedicated secure password managers instead. 4) Monitor and restrict physical and remote access to user workstations to prevent unauthorized access to stored browser data. 5) Apply network segmentation and access controls to limit exposure of FAST/TOOLS interfaces to trusted users only. 6) Stay alert for vendor patches or updates addressing this vulnerability and apply them promptly once available. 7) Consider deploying browser security extensions or enterprise policies that disable autofill features for critical applications. These targeted measures will reduce the risk of sensitive data leakage through browser caching in the context of this vulnerability.