CVE-2025-6701 is an open redirect vulnerability identified in version 1.1.0 of the Xuxueli xxl-sso product, a single sign-on (SSO) solution. The vulnerability arises from improper validation or sanitization of the 'redirect_url' parameter in the /xxl-sso-server/doLogin endpoint. An attacker can manipulate this parameter to redirect users to arbitrary external URLs after login attempts. This flaw is exploitable remotely without requiring authentication, although user interaction is necessary since the victim must click a crafted link or be redirected through social engineering or phishing tactics. The vulnerability has been publicly disclosed, but no patch or vendor response has been issued as of the publication date. The CVSS 4.0 base score is 5.1 (medium severity), reflecting network attack vector, low attack complexity, no privileges required, but user interaction needed, and limited impact on confidentiality and integrity. Open redirect vulnerabilities primarily facilitate phishing, credential theft, or malware distribution by abusing trusted domains to lure victims. While the direct impact on system integrity or availability is low, the risk lies in enabling social engineering attacks that can lead to further compromise. Since xxl-sso is an SSO system, exploitation could undermine user trust and potentially facilitate session hijacking or credential interception if combined with other vulnerabilities or attacks. The lack of vendor response and absence of patches increases the window of exposure for organizations using this version. The vulnerability affects only version 1.1.0, and no information about other versions is provided.

For European organizations, the open redirect vulnerability in xxl-sso 1.1.0 poses a moderate risk primarily through social engineering and phishing campaigns leveraging trusted internal authentication portals. Since SSO systems are central to user authentication across multiple services, successful exploitation could erode user confidence and potentially serve as a stepping stone for more sophisticated attacks such as credential harvesting or session hijacking. Organizations relying on xxl-sso 1.1.0 for authentication may face increased phishing risks, potentially leading to unauthorized access if users are tricked into visiting malicious sites via manipulated redirects. The vulnerability does not directly compromise system confidentiality or availability but can indirectly facilitate data breaches or malware infections. Given the public disclosure and lack of vendor mitigation, European entities using this software should consider the threat significant enough to warrant immediate attention, especially in sectors with high-value targets such as finance, government, and critical infrastructure. The medium severity rating suggests that while the vulnerability is not critical, it should not be ignored due to the potential for exploitation in targeted phishing campaigns.

1. Immediate mitigation should include implementing strict input validation and sanitization on the 'redirect_url' parameter to ensure only safe, internal URLs are accepted. This can be done by enforcing allowlists of valid redirect destinations or using relative paths rather than full URLs. 2. If modifying the application code is not immediately feasible, deploy web application firewall (WAF) rules to detect and block requests with suspicious or external redirect_url parameters. 3. Educate users and administrators about the risk of phishing attacks exploiting this vulnerability, emphasizing caution with unexpected login redirects. 4. Monitor authentication logs for unusual redirect patterns or spikes in failed login attempts that may indicate exploitation attempts. 5. Consider temporarily disabling or restricting the use of the vulnerable endpoint if possible until a vendor patch or official fix is available. 6. Engage with the vendor or community to seek updates or patches and track any future advisories. 7. For long-term mitigation, upgrade to a patched version once available or consider alternative SSO solutions with robust security track records. 8. Implement multi-factor authentication (MFA) to reduce the impact of credential theft stemming from phishing enabled by this vulnerability.