CVE-2025-39381 is a Cross-Site Request Forgery (CSRF) vulnerability identified in Kiotviet's KiotViet Sync product, affecting versions up to and including 1.8.4. The vulnerability allows an attacker to perform unauthorized actions on behalf of an authenticated user by exploiting the lack of proper CSRF protections. Specifically, this vulnerability can lead to Stored Cross-Site Scripting (Stored XSS), where malicious scripts injected by the attacker are persistently stored on the server and executed in the context of other users' browsers. The combination of CSRF and Stored XSS significantly increases the attack surface, as CSRF can be used to inject malicious payloads that are then stored and executed later. KiotViet Sync is a synchronization tool likely used for business or retail operations, facilitating data synchronization between systems or cloud services. The vulnerability does not currently have known exploits in the wild, and no patches have been published at the time of this report. The technical details confirm the vulnerability is categorized under CWE-352, indicating a failure to implement anti-CSRF tokens or equivalent protections. Exploitation requires the victim to be authenticated to the KiotViet Sync service and to visit a maliciously crafted webpage or link that triggers the CSRF attack. Once exploited, attackers can execute arbitrary scripts in the victim's browser, potentially leading to session hijacking, data theft, or unauthorized actions within the application.

For European organizations using KiotViet Sync, this vulnerability poses a moderate risk primarily to confidentiality and integrity. The Stored XSS resulting from CSRF exploitation can allow attackers to steal session cookies, impersonate users, or manipulate data within the application. This can lead to unauthorized access to sensitive business data, disruption of synchronization processes, or manipulation of inventory or sales data if KiotViet Sync is integrated with retail or ERP systems. The impact on availability is less direct but could occur if attackers use the vulnerability to inject disruptive scripts or trigger application errors. Given that KiotViet Sync is a synchronization tool, any compromise could affect data consistency across systems, potentially leading to operational disruptions. The absence of known exploits reduces immediate risk, but the medium severity rating and the nature of the vulnerability warrant proactive mitigation. European organizations with retail, supply chain, or business operations relying on KiotViet Sync should be particularly vigilant, as exploitation could undermine business continuity and data integrity.

1. Implement and enforce anti-CSRF tokens in all state-changing requests within KiotViet Sync to prevent unauthorized request forgery. 2. Conduct a thorough code review and input validation to sanitize all user inputs and outputs, eliminating Stored XSS vectors. 3. Restrict the use of cookies with the SameSite attribute set to 'Strict' or 'Lax' to reduce CSRF attack surface. 4. Educate users to avoid clicking on suspicious links or visiting untrusted websites while authenticated to KiotViet Sync. 5. Monitor application logs for unusual activities that may indicate exploitation attempts, such as unexpected POST requests or script injections. 6. Coordinate with Kiotviet for timely patch releases and apply updates promptly once available. 7. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts in browsers. 8. Use web application firewalls (WAFs) configured to detect and block CSRF and XSS attack patterns targeting KiotViet Sync endpoints. 9. Limit user privileges within KiotViet Sync to the minimum necessary to reduce the impact of a compromised account. 10. Regularly audit and test the application for CSRF and XSS vulnerabilities using automated tools and manual penetration testing.