CVE-2025-59896 in Sync Breeze Enterprise Server
Summary
by MITRE • 01/28/2026
Sync Breeze Enterprise Server v10.4.18 and Disk Pulse Enterprise v10.4.18 contain a persistent authenticated Cross-Site Scripting (XSS) vulnerability. An attacker could send malicious content to an authenticated user and steal information from their session due to insufficient validation of user input in '/add_command?sid=', affecting the 'command_name' parameter.
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Analysis
by VulDB Data Team • 02/11/2026
The vulnerability identified as CVE-2025-59896 represents a critical persistent cross-site scripting flaw affecting Sync Breeze Enterprise Server version 10.4.18 and Disk Pulse Enterprise version 10.4.18. This vulnerability resides within the web interface of these enterprise file synchronization and monitoring solutions, specifically in the '/add_command?sid=' endpoint where user input is inadequately validated. The affected 'command_name' parameter serves as the primary vector for exploitation, allowing attackers to inject malicious JavaScript code that persists in the application's database or configuration files. Security researchers have classified this as a persistent XSS vulnerability due to the fact that malicious payloads stored in the system can be executed against any user who accesses the affected functionality, making it particularly dangerous in enterprise environments where multiple administrators may interact with the same system.
The technical implementation of this vulnerability stems from inadequate input sanitization and output encoding practices within the web application's parameter handling mechanisms. When an authenticated user submits a command name containing malicious script code through the vulnerable endpoint, the application fails to properly validate or escape the input before storing it in the system. This allows the attacker's payload to be stored in the application's persistent storage and subsequently executed whenever the affected page is rendered to any user who views the command list or related interface elements. The vulnerability requires an authenticated session to exploit, meaning that attackers must first gain valid credentials to the system, but once achieved, the persistent nature of the vulnerability allows for widespread impact across multiple users without requiring repeated exploitation attempts.
The operational impact of this vulnerability extends beyond simple session hijacking, as it creates a persistent threat vector that can be leveraged for various malicious activities within the enterprise environment. An attacker with access to an authenticated user session can craft malicious command names that, when executed, could redirect users to phishing sites, steal session cookies, or even execute additional malicious payloads through the browser's execution context. The vulnerability affects enterprise file monitoring and synchronization systems, making it particularly concerning for organizations that rely on these tools for critical data management operations. The persistence of the vulnerability means that even after initial exploitation, the malicious code continues to execute against any user who accesses the affected functionality, potentially allowing for extended reconnaissance, data exfiltration, or lateral movement within the network. This aligns with ATT&CK technique T1566.001 for initial access through phishing and T1071.001 for application layer protocol usage, as the vulnerability enables attackers to establish persistent presence within the enterprise environment.
Organizations should implement immediate mitigations including input validation and output encoding for all user-supplied data within the affected applications, particularly focusing on the command_name parameter in the /add_command endpoint. The recommended approach involves implementing strict validation rules that reject or sanitize any input containing potentially dangerous script characters, while also ensuring that all stored data is properly encoded before being rendered in the browser context. Security patches should be applied immediately upon availability from the vendor, as these enterprise file management solutions are critical infrastructure components that require continuous monitoring and protection. Additionally, organizations should consider implementing web application firewalls and content security policies to provide additional layers of defense against similar vulnerabilities, while also conducting regular security assessments to identify other potential XSS vulnerabilities within their enterprise applications. The vulnerability demonstrates the importance of following CWE guidelines for input validation and output encoding, specifically addressing CWE-79 which covers cross-site scripting vulnerabilities, and implementing proper secure coding practices to prevent persistent XSS attacks in enterprise web applications.