CVE-2025-13515 is a reflected Cross-Site Scripting (XSS) vulnerability identified in the Nouri.sh Newsletter plugin for WordPress, affecting all versions up to and including 1.0.1.3. The vulnerability stems from insufficient sanitization and escaping of the $_SERVER['PHP_SELF'] parameter during web page generation. This parameter, which typically contains the current script's filename, can be manipulated by an attacker to inject arbitrary JavaScript code. Since the plugin fails to properly neutralize this input, an attacker can craft a malicious URL containing script payloads that, when clicked by an unsuspecting user, executes in the context of the victim's browser. The attack does not require any authentication but does require user interaction, such as clicking a link. The reflected nature means the malicious script is not stored on the server but reflected off the vulnerable page. The CVSS 3.1 base score of 6.1 reflects a medium severity, with attack vector being network (remote), low attack complexity, no privileges required, but requiring user interaction. The impact affects confidentiality and integrity, potentially allowing theft of session cookies, user credentials, or performing unauthorized actions on behalf of the user. No known exploits have been reported in the wild yet, but the vulnerability is publicly disclosed and thus poses a risk. The plugin is used in WordPress environments, which are widely deployed for websites globally, including in Europe. The vulnerability is classified under CWE-79, a common and well-understood web application security issue. Mitigation currently lacks an official patch but can be addressed by applying proper input validation and output encoding on the affected parameter, or by disabling the plugin until a fix is released. Additional mitigations include deploying Content Security Policy (CSP) headers to restrict script execution and user education to avoid clicking suspicious links.

For European organizations, this vulnerability poses a moderate risk primarily to websites using the Nouri.sh Newsletter plugin on WordPress. Exploitation can lead to theft of sensitive user data such as session cookies or personal information, enabling account hijacking or unauthorized actions. This can damage organizational reputation, lead to regulatory non-compliance under GDPR due to data breaches, and potentially cause financial losses. Public-facing websites, especially those handling user registrations, subscriptions, or sensitive communications, are at higher risk. The reflected XSS nature means attacks require user interaction, which may limit large-scale automated exploitation but targeted phishing campaigns could be effective. The vulnerability affects confidentiality and integrity but does not impact availability. Given the widespread use of WordPress in Europe, especially among small and medium enterprises, the threat surface is significant. Organizations in sectors such as e-commerce, media, and communications that rely on newsletters for customer engagement are particularly vulnerable. The absence of known exploits in the wild reduces immediate risk but the public disclosure increases the likelihood of future exploitation attempts.

1. Monitor for and apply official patches or updates from the plugin vendor as soon as they become available. 2. Until a patch is released, consider disabling the Nouri.sh Newsletter plugin to eliminate the attack vector. 3. Implement strict input validation and output encoding on the $_SERVER['PHP_SELF'] parameter or any user-controllable inputs within the plugin code if custom modifications are possible. 4. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 5. Educate users and administrators about the risks of clicking suspicious links, especially those that appear to come from the organization's domain but contain unusual URL parameters. 6. Use Web Application Firewalls (WAFs) with rules designed to detect and block reflected XSS payloads targeting this plugin. 7. Regularly audit WordPress plugins and themes for vulnerabilities and remove unused or unsupported plugins. 8. Employ security headers such as X-XSS-Protection and HttpOnly flags on cookies to mitigate exploitation impact. 9. Monitor web server logs for suspicious requests containing script payloads in URL parameters to detect potential exploitation attempts early.