CVE-2025-5770 is a reflected cross-site scripting (XSS) vulnerability identified in the authentication endpoints of WSO2 Identity Server versions 6.0.0, 6.1.0, 7.0.0, and 7.1.0. The root cause is improper neutralization of input during web page generation (CWE-79), specifically a lack of output encoding on user-supplied input reflected in authentication responses. This allows an attacker to craft malicious URLs containing JavaScript payloads that, when visited by a victim, execute in the victim's browser context. Potential attack vectors include redirecting users to malicious websites, manipulating the user interface to deceive users, or accessing sensitive data accessible via the browser. The vulnerability does not allow direct session hijacking because session cookies are protected with the httpOnly flag, preventing JavaScript access to cookies. The CVSS 3.1 score is 6.1, reflecting medium severity with network attack vector, low attack complexity, no privileges required, but requiring user interaction. The scope is changed as the vulnerability affects the confidentiality and integrity of user data within the browser context. No public exploits have been reported yet, but the vulnerability is publicly disclosed and should be addressed promptly. WSO2 Identity Server is widely used in enterprise environments for identity and access management, making this vulnerability relevant to organizations relying on it for authentication services.

For European organizations, exploitation of this vulnerability could lead to unauthorized access to sensitive information displayed or accessible via the authentication interface, phishing through UI manipulation, and redirection to malicious sites that could further compromise users. While session hijacking is mitigated, the ability to execute arbitrary scripts in the browser can undermine user trust and lead to data leakage or credential theft through social engineering. Organizations in sectors such as finance, government, healthcare, and critical infrastructure that rely on WSO2 Identity Server for authentication are particularly at risk. The impact is compounded in environments where users access the identity server from browsers without additional security controls like Content Security Policy (CSP). The vulnerability could also be leveraged as part of a broader attack chain targeting enterprise networks. Given the medium severity and the requirement for user interaction, the threat is moderate but significant enough to warrant immediate remediation to prevent exploitation.

Organizations should apply patches or updates from WSO2 as soon as they become available to address this vulnerability. In the absence of patches, implement strict input validation and output encoding on all user-supplied data reflected in authentication endpoints. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Educate users to avoid clicking on suspicious links and implement multi-factor authentication to reduce the impact of potential credential theft. Monitor authentication logs for unusual activity that could indicate exploitation attempts. Consider deploying web application firewalls (WAFs) with rules to detect and block reflected XSS payloads targeting WSO2 Identity Server endpoints. Regularly review and update security configurations of identity management systems to minimize attack surface. Finally, conduct security assessments and penetration testing focused on authentication workflows to identify and remediate similar issues proactively.