CVE-2025-40697 is a reflected Cross-Site Scripting (XSS) vulnerability categorized under CWE-79, discovered in the Lewe WebMeasure product. The vulnerability exists in the '/index.php' script, specifically in the handling of the 'page' parameter. Because the input is improperly neutralized during web page generation, an attacker can craft a malicious URL that injects arbitrary JavaScript code. When a victim accesses this URL, the injected script executes within their browser context, allowing the attacker to steal session cookies, hijack user sessions, or perform actions with the victim's privileges. The vulnerability is remotely exploitable without authentication and requires user interaction (clicking a malicious link). The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:A), and low scope impact (S:C). The vulnerability was reserved in April 2025 and published in February 2026. No patches or known exploits are currently available. The lack of patches means organizations must rely on mitigation strategies until an official fix is released. This vulnerability primarily threatens confidentiality and integrity of user data and sessions, with limited direct impact on availability. Given that Lewe WebMeasure is a web analytics tool, the attack surface is primarily public-facing web servers that process user input via the 'page' parameter.

For European organizations, the impact of CVE-2025-40697 can be significant if Lewe WebMeasure is deployed on public-facing web properties. Successful exploitation can lead to theft of session cookies and sensitive user data, enabling attackers to impersonate users or escalate privileges. This can result in unauthorized access to internal analytics data or user accounts, potentially leading to data breaches or reputational damage. Since the vulnerability requires user interaction, phishing or social engineering campaigns could be used to lure victims into triggering the exploit. Organizations handling sensitive customer or internal data through Lewe WebMeasure are at risk of confidentiality breaches. Additionally, attackers could perform unauthorized actions on behalf of users, impacting data integrity. Although no direct availability impact is expected, the indirect consequences of compromised user sessions could disrupt business operations or lead to regulatory non-compliance under GDPR if personal data is exposed.

1. Implement strict input validation and output encoding on the 'page' parameter in '/index.php' to ensure that any user-supplied data is properly sanitized before rendering. 2. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in the browser context. 3. Use web application firewalls (WAFs) with updated rules to detect and block common XSS attack patterns targeting Lewe WebMeasure. 4. Educate users and administrators about phishing risks and the importance of not clicking suspicious links that could trigger reflected XSS. 5. Monitor web server logs and analytics for unusual request patterns or error messages related to the 'page' parameter. 6. Segregate and limit access to the analytics platform to reduce the impact of potential session hijacking. 7. Stay alert for official patches or updates from Lewe and apply them promptly once available. 8. Consider implementing multi-factor authentication (MFA) on user accounts to mitigate session hijacking risks. 9. Conduct regular security assessments and penetration tests focusing on web input handling to identify similar vulnerabilities.