CVE-2025-5887 is a cross-site scripting (XSS) vulnerability identified in version 1.0 of the jsnjfz WebStack-Guns product, specifically within an unknown function in the UserMgrController.java file related to the File Upload component. The vulnerability arises from improper sanitization or validation of the 'File' argument, allowing an attacker to inject malicious scripts. This flaw can be exploited remotely without requiring authentication, although user interaction is necessary to trigger the malicious payload. The vulnerability has been publicly disclosed, and while no known exploits are currently observed in the wild, the availability of exploit details increases the risk of exploitation. The vendor has not responded to notifications regarding this issue, and no patches or mitigations have been provided to date. The CVSS v4.0 base score is 5.1, categorizing it as a medium severity vulnerability. The vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L) but user interaction needed (UI:P), with limited impact on integrity and no impact on confidentiality or availability. This vulnerability enables attackers to execute arbitrary scripts in the context of the victim's browser, potentially leading to session hijacking, credential theft, or unauthorized actions within the affected web application.

For European organizations using jsnjfz WebStack-Guns 1.0, this vulnerability poses a moderate risk. Exploitation could lead to compromise of user sessions, theft of sensitive information, or unauthorized actions performed on behalf of legitimate users. This is particularly concerning for organizations handling personal data under GDPR, as successful attacks could result in data breaches and regulatory penalties. The remote exploitability and lack of vendor response increase the urgency for organizations to implement mitigations. While the impact on system availability and confidentiality is limited, the integrity of user interactions and trust in the affected web applications could be undermined. Industries with high reliance on web-based user management systems, such as financial services, healthcare, and e-commerce, may face increased risks. Additionally, the need for user interaction means phishing or social engineering could be used to trigger the exploit, amplifying the threat in environments with less security awareness.

Given the absence of official patches, European organizations should implement immediate compensating controls. These include: 1) Applying strict input validation and output encoding on the File Upload component to sanitize user inputs and prevent script injection. 2) Employing Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 3) Enhancing user awareness training to recognize and avoid suspicious links or file uploads that could trigger XSS attacks. 4) Utilizing web application firewalls (WAFs) configured to detect and block XSS payloads targeting the vulnerable endpoint. 5) Monitoring application logs and network traffic for anomalous activities indicative of exploitation attempts. 6) Considering isolation or temporary disabling of the vulnerable File Upload functionality if feasible until a vendor patch or update is available. 7) Planning for migration or upgrade to a more secure version or alternative product if the vendor remains unresponsive.