CVE-2025-61539 identifies a cross-site scripting (XSS) vulnerability in Ultimate PHP Board version 2.2.7, specifically through the u_name parameter in the lostpassword.php script. This vulnerability arises because the application fails to properly sanitize or encode user-supplied input before reflecting it back in the web page, allowing an attacker to inject malicious JavaScript code. The attack vector is remote and requires no authentication, but it does require user interaction, such as clicking a crafted link or visiting a malicious page that triggers the payload. The vulnerability impacts confidentiality and integrity by enabling attackers to steal session cookies, perform actions on behalf of users, or manipulate displayed content. Availability is not impacted. The CVSS 3.1 base score is 6.1, indicating medium severity, with a vector string AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. No patches or known exploits are currently available, but the vulnerability is publicly disclosed. The CWE-79 classification confirms this is a classic reflected XSS issue. Organizations running this forum software should assess their exposure and implement mitigations promptly.

For European organizations, exploitation of this XSS vulnerability could lead to unauthorized disclosure of user session tokens or credentials, enabling account takeover or impersonation within the affected forum environment. This can result in reputational damage, loss of user trust, and potential data leakage. Since Ultimate PHP Board is often used for community engagement, compromised forums could be leveraged to distribute malware or phishing links to users. The vulnerability does not directly impact system availability but can facilitate further attacks that degrade service integrity. Organizations handling sensitive user data or operating critical community platforms are at higher risk. The need for user interaction limits mass exploitation but targeted spear-phishing campaigns could be effective. The absence of known exploits reduces immediate risk but should not lead to complacency.

1. Apply any available patches or updates from Ultimate PHP Board developers as soon as they are released. 2. Implement strict input validation and output encoding on the u_name parameter and all user-supplied inputs to prevent script injection. 3. Employ Content Security Policy (CSP) headers to restrict execution of unauthorized scripts. 4. Educate users about the risks of clicking unknown links and recognizing phishing attempts. 5. Monitor web server logs and application behavior for suspicious requests targeting lostpassword.php. 6. Consider deploying Web Application Firewalls (WAFs) with rules to detect and block XSS payloads. 7. Regularly audit and test web applications for XSS and other injection vulnerabilities. 8. Limit the privileges of forum users to reduce impact if an account is compromised.