CVE-2025-5377 is a cross-site scripting (XSS) vulnerability identified in Astun Technology's iShare Maps version 5.4.0. The vulnerability specifically affects the 'historic1.asp' file, where the 'Zoom' parameter can be manipulated by an attacker to inject malicious scripts. This vulnerability is classified as a reflected XSS, as the attack vector involves sending a crafted request with a malicious payload in the Zoom argument, which is then reflected back in the web application response without proper sanitization or encoding. The vulnerability can be exploited remotely without requiring authentication, making it accessible to any attacker who can reach the affected web interface. The CVSS v4.0 base score is 5.3, indicating a medium severity level. The attack requires user interaction, such as tricking a user into clicking a malicious link or visiting a crafted webpage that includes the exploit. The vendor was notified early but has not responded or provided a patch, and no known exploits have been observed in the wild yet. The lack of vendor response and patch availability increases the risk of exploitation as attackers may develop and share exploit code publicly. The vulnerability impacts the confidentiality and integrity of user sessions by potentially allowing attackers to execute arbitrary JavaScript in the context of the victim's browser, which can lead to session hijacking, credential theft, or unauthorized actions within the application. However, the vulnerability does not directly affect availability or require elevated privileges, limiting its overall impact to medium severity.

For European organizations using Astun Technology's iShare Maps 5.4.0, this XSS vulnerability poses a risk primarily to the confidentiality and integrity of user data and sessions. Organizations relying on iShare Maps for geographic information system (GIS) services, especially those providing public or internal mapping services, could see attackers exploit this flaw to conduct phishing attacks, steal session cookies, or perform unauthorized actions on behalf of legitimate users. This could lead to data leakage or unauthorized access to sensitive mapping data or related services. Since the vulnerability requires user interaction, the risk is heightened in environments where users are less security-aware or where social engineering campaigns are prevalent. The absence of a patch and vendor response increases the window of exposure. Additionally, if iShare Maps is integrated with other critical systems or portals, the XSS could serve as a pivot point for further attacks. The impact on European organizations is also influenced by compliance requirements such as GDPR, where data breaches involving personal data could lead to regulatory penalties. Overall, while the vulnerability does not directly compromise system availability, the potential for data compromise and unauthorized actions makes it a significant concern for affected organizations.

Given the lack of an official patch from Astun Technology, European organizations should implement several practical mitigations: 1) Employ Web Application Firewalls (WAFs) with custom rules to detect and block malicious payloads targeting the 'Zoom' parameter in the historic1.asp endpoint. 2) Implement strict input validation and output encoding at the application or proxy level to neutralize script injection attempts. 3) Use Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 4) Educate users about the risks of clicking on suspicious links and encourage cautious behavior when interacting with mapping services. 5) Monitor web server logs and application telemetry for unusual requests or error patterns related to the vulnerable parameter. 6) If feasible, isolate the iShare Maps application behind a VPN or restrict access to trusted users to reduce exposure. 7) Consider deploying a reverse proxy that sanitizes inputs or performs additional security checks. 8) Engage with Astun Technology for updates and consider alternative GIS solutions if the vendor remains unresponsive. These steps go beyond generic advice by focusing on compensating controls and user awareness in the absence of a vendor patch.