CVE-2025-53820 is a Reflected Cross-Site Scripting (XSS) vulnerability identified in the WeGIA web management application developed by LabRedesCefetRJ. WeGIA is an open-source platform primarily targeting Portuguese language users and charitable institutions. The vulnerability exists in the 'index.php' endpoint, specifically in the handling of the 'erro' parameter, which fails to properly neutralize user-supplied input before reflecting it back in the web page. This improper input sanitization allows an attacker to inject malicious JavaScript code that executes in the context of the victim's browser when they visit a crafted URL containing the malicious payload. The vulnerability affects all versions prior to 3.4.5, with the vendor having released a patch in version 3.4.5 to address the issue. The CVSS v3.1 base score is 6.5 (medium severity), with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), high impact on confidentiality (C:H), and no impact on integrity or availability (I:N/A:N). This means an attacker can remotely exploit the vulnerability without authentication but requires the victim to interact by clicking a malicious link or visiting a crafted page. The primary risk is the theft of sensitive information such as session cookies or credentials, potentially leading to account hijacking or unauthorized access. No known exploits are currently reported in the wild, but the vulnerability is publicly disclosed, increasing the risk of exploitation attempts.

For European organizations using WeGIA, particularly those in the charitable sector or Portuguese-speaking communities, this vulnerability poses a significant risk to confidentiality. Attackers could leverage the XSS flaw to steal session tokens or other sensitive data, enabling unauthorized access to user accounts or administrative functions. This could lead to data breaches involving donor information, financial data, or internal communications. Additionally, successful exploitation could facilitate phishing attacks or malware distribution by injecting malicious scripts into trusted web pages. Although the vulnerability does not directly affect integrity or availability, the loss of confidentiality and potential subsequent attacks could disrupt organizational operations and damage reputation. Given the focus on charitable institutions, which may have limited cybersecurity resources, the impact could be more pronounced. Furthermore, the requirement for user interaction means social engineering or targeted phishing campaigns could be used to increase exploitation success. The medium severity score reflects these factors but also indicates that the threat should not be underestimated, especially in environments with high-value data or critical services.

European organizations using WeGIA should immediately upgrade to version 3.4.5 or later, which contains the official patch for this vulnerability. If upgrading is not immediately feasible, organizations should implement input validation and output encoding on the 'erro' parameter to neutralize potentially malicious scripts. Web Application Firewalls (WAFs) can be configured with custom rules to detect and block suspicious payloads targeting the 'erro' parameter. Additionally, organizations should conduct user awareness training to reduce the risk of users clicking on malicious links, emphasizing caution with unsolicited URLs. Regular security assessments and penetration testing should include checks for XSS vulnerabilities. Monitoring web server logs for unusual requests to 'index.php' with suspicious 'erro' parameter values can help detect exploitation attempts. Finally, implementing Content Security Policy (CSP) headers can mitigate the impact of XSS by restricting the execution of unauthorized scripts in browsers.