CVE-2025-59897 is a persistent Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting Flexense Sync Breeze Enterprise Server version 10.4.18. The vulnerability is located in the web interface endpoint '/edit_command?sid=', where the 'source_dir' and 'dest_dir' parameters fail to properly sanitize or neutralize user-supplied input before rendering it in web pages. This improper input handling allows an authenticated attacker to inject malicious JavaScript code that is stored persistently on the server and executed in the browsers of other authenticated users accessing the affected pages. The attack vector requires the attacker to be authenticated with at least low privileges, and the victim must interact with the malicious content for exploitation to succeed. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L - low privileges), user interaction required (UI:P), and low scope impact (SC:L). The vulnerability does not impact confidentiality, integrity, or availability directly but can lead to session hijacking or information disclosure through stolen cookies or tokens. No patches or exploit code are currently publicly available, but the vulnerability's presence in enterprise server software used for file synchronization and monitoring makes it a concern for organizations relying on this product for critical operations.

For European organizations, this vulnerability poses a moderate risk primarily through potential session hijacking and unauthorized access to sensitive information within the Sync Breeze Enterprise Server environment. Since the vulnerability requires authentication, it limits exposure to internal or trusted users, but insider threats or compromised accounts could be leveraged for exploitation. The persistent nature of the XSS means malicious scripts can affect multiple users over time, increasing the risk of data leakage or lateral movement within the network. Organizations using Sync Breeze Enterprise Server for file synchronization and monitoring in regulated sectors such as finance, healthcare, or critical infrastructure could face compliance and operational risks if attackers exploit this vulnerability. Additionally, stolen session data could facilitate further attacks or unauthorized data access, undermining confidentiality and trust in enterprise systems.

Organizations should immediately review and restrict access to the Sync Breeze Enterprise Server web interface, ensuring only trusted and necessary users have authenticated access. Implement strict input validation and output encoding on the 'source_dir' and 'dest_dir' parameters to neutralize potentially malicious scripts. Although no official patch is currently available, monitoring vendor advisories for updates is critical. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the vulnerable parameters. Conduct regular security awareness training to reduce the risk of social engineering that could facilitate exploitation. Additionally, enforce multi-factor authentication (MFA) to reduce the risk of compromised credentials being used to exploit this vulnerability. Regularly audit logs for unusual activity related to the '/edit_command' endpoint and consider network segmentation to limit the impact of potential breaches.