CVE-2025-67438 is a stored cross-site scripting (XSS) vulnerability found in Sync-in Server versions prior to 1.9.3. This vulnerability arises because the application insufficiently sanitizes SVG file uploads, allowing an authenticated attacker to embed malicious JavaScript payloads within crafted SVG files. When other users access or preview these SVG files within the application, the embedded script executes in their browsers under the context of the vulnerable domain. This execution can lead to the theft of sensitive data such as session cookies, enabling attackers to hijack user sessions and potentially escalate privileges or access confidential information. The attack vector requires the attacker to have valid credentials to upload the malicious SVG, but no further user interaction is necessary beyond the victim viewing the file. The vulnerability is classified as stored XSS because the malicious payload is persistently stored on the server and served to multiple users. No CVSS score has been assigned yet, and no public exploits have been reported. The lack of official patches at the time of publication indicates that organizations must implement interim mitigations. This vulnerability highlights the risks associated with improper input validation and output encoding in file upload features, especially for complex file formats like SVG that can contain executable code.

The primary impact of CVE-2025-67438 is on the confidentiality and integrity of user sessions and data within Sync-in Server environments. Successful exploitation allows attackers to execute arbitrary JavaScript in the context of other users, leading to session hijacking, unauthorized data access, and potentially lateral movement within the affected network. This can result in the compromise of sensitive organizational information, disruption of collaboration workflows, and erosion of user trust. Because the vulnerability requires authentication to upload the malicious SVG, the attacker must already have some level of access, but the ability to escalate privileges or impersonate other users significantly raises the threat level. Organizations relying on Sync-in Server for internal or external collaboration are at risk of data breaches and operational disruption. The absence of known exploits in the wild currently limits immediate widespread impact, but the vulnerability's nature makes it a prime target for attackers once exploit code becomes available. The impact is magnified in environments with high user interaction with uploaded files and where session cookies grant broad access.

To mitigate CVE-2025-67438, organizations should first upgrade Sync-in Server to version 1.9.3 or later once an official patch is released. Until then, implement strict file upload controls by restricting allowed file types and scanning SVG files for embedded scripts or suspicious content. Employ Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of XSS attacks. Enforce least privilege principles to limit user permissions for uploading files, ensuring only trusted users can upload SVGs. Additionally, implement robust input validation and output encoding on the server side to sanitize SVG content before storage or rendering. Monitor logs for unusual upload activity and user behavior indicative of exploitation attempts. Educate users to avoid interacting with suspicious files and maintain strong authentication mechanisms to reduce the risk of compromised accounts. Finally, conduct regular security assessments and penetration testing focused on file upload functionalities to detect similar vulnerabilities proactively.