CVE-2025-6551 is a cross-site scripting (XSS) vulnerability identified in version 1.0.0 of the java-aodeng Hope-Boot framework. The vulnerability resides in the Login function within the WebController.java source file, specifically in the handling of the 'errorMsg' argument. Improper sanitization or validation of this parameter allows an attacker to inject malicious scripts that execute in the context of the victim's browser. This flaw can be exploited remotely without requiring authentication, although user interaction is necessary for the malicious payload to execute (e.g., the victim must visit a crafted URL or interact with a manipulated login page). The vulnerability has been publicly disclosed, and while no known exploits are currently observed in the wild, the availability of public information increases the risk of exploitation attempts. The vendor has not responded to notifications about this issue, and no patches or mitigations have been provided at this time. The CVSS 4.0 base score is 5.1, reflecting a medium severity level, with factors including network attack vector, low attack complexity, no privileges required, but requiring user interaction and limited impact on confidentiality and integrity. The vulnerability primarily threatens the confidentiality and integrity of user sessions by enabling script injection, which can lead to session hijacking, credential theft, or defacement of the login interface. The availability impact is negligible. Since the vulnerability affects a specific version of Hope-Boot, the scope is limited to organizations using this framework version in their web applications.

For European organizations using java-aodeng Hope-Boot 1.0.0, this vulnerability poses a risk of client-side attacks that can compromise user credentials and session integrity. Attackers could leverage the XSS flaw to steal authentication tokens, perform phishing attacks, or execute malicious scripts that manipulate user interactions. This can lead to unauthorized access to sensitive systems or data breaches, especially if the affected applications handle critical business functions or personal data subject to GDPR regulations. The medium severity indicates that while the vulnerability is not trivially exploitable without user interaction, the potential for damage exists in environments with high user traffic or where users have elevated privileges. Additionally, the lack of vendor response and absence of patches increase the window of exposure. Organizations in sectors such as finance, healthcare, and government, which often deploy custom or third-party Java frameworks, may face reputational damage and regulatory penalties if exploited. The vulnerability does not directly affect system availability but can indirectly disrupt operations through compromised accounts or trust.

Given the absence of official patches, European organizations should implement immediate compensating controls. First, apply strict input validation and output encoding on the 'errorMsg' parameter at the application level to neutralize malicious scripts. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Use Web Application Firewalls (WAFs) configured with custom rules to detect and block suspicious payloads targeting the vulnerable endpoint. Conduct thorough code reviews to identify similar unsanitized inputs in the application. Educate users about phishing risks and suspicious links to reduce the likelihood of successful exploitation. Monitor web server logs for unusual request patterns or error messages that may indicate attempted exploitation. Where feasible, isolate or restrict access to applications running Hope-Boot 1.0.0 to trusted networks until a vendor patch or upgrade is available. Finally, consider migrating to alternative frameworks or updated versions once they become available to eliminate the vulnerability.