CVE-2025-57393 is a high-severity stored cross-site scripting (XSS) vulnerability affecting the Kissflow Work Platform, specifically the Kissflow Application versions from 2.0 up to 4.2v. This vulnerability allows an attacker to inject malicious scripts or HTML code into the application, which are then stored and executed in the context of other users' browsers when they access the affected content. The vulnerability is categorized under CWE-79, which is a common weakness related to improper neutralization of input during web page generation. The CVSS 3.1 base score of 8.8 reflects the critical nature of this vulnerability, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), indicating that exploitation can lead to full compromise of user data, session hijacking, and potentially disruption of service. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a significant risk. The lack of patch links suggests that a fix may not yet be publicly available, emphasizing the need for immediate mitigation efforts. Stored XSS vulnerabilities are particularly dangerous because the malicious payload persists on the server and affects multiple users, increasing the attack surface and potential damage. Attackers can leverage this to steal sensitive information, perform actions on behalf of users, or deliver further malware.

For European organizations using the Kissflow Work Platform, this vulnerability poses a substantial risk. Kissflow is a widely used business process management and workflow automation tool, often employed in sectors such as finance, healthcare, government, and manufacturing. Exploitation of this XSS vulnerability could lead to unauthorized access to sensitive corporate data, user credential theft, and manipulation of business workflows. This could result in data breaches, regulatory non-compliance (e.g., GDPR violations), financial losses, and reputational damage. The high impact on confidentiality, integrity, and availability means that attackers could not only exfiltrate data but also alter or disrupt critical business processes. Given the collaborative nature of Kissflow, the vulnerability could facilitate lateral movement within organizations, amplifying the threat. Additionally, the requirement for user interaction means phishing or social engineering could be used to trigger the exploit, increasing the risk in environments with less security awareness. The absence of known exploits in the wild does not diminish the urgency, as public disclosure often leads to rapid development of exploit code.

European organizations should implement a multi-layered mitigation strategy beyond generic advice: 1) Immediate deployment of web application firewalls (WAFs) with custom rules to detect and block typical XSS payload patterns targeting Kissflow. 2) Conduct thorough input validation and output encoding on all user-supplied data within Kissflow workflows and forms, if customization is possible. 3) Restrict user permissions to the minimum necessary to reduce the impact of potential exploitation, especially limiting who can input or approve data in workflows. 4) Enhance user awareness training focused on recognizing phishing attempts that could trigger the stored XSS. 5) Monitor application logs and user activity for unusual behavior indicative of exploitation attempts. 6) Engage with Kissflow support or vendor channels to obtain patches or updates as soon as they become available, and plan for rapid deployment. 7) Consider isolating or segmenting the Kissflow environment within the network to limit lateral movement in case of compromise. 8) Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers accessing Kissflow. These targeted actions will help reduce the attack surface and mitigate the risk until a permanent fix is applied.