CVE-2025-46459 is a Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the 'Confirm User Registration' plugin developed by Ralf Hortt, up to version 2.1.5. Stored XSS occurs when malicious input is improperly neutralized and subsequently stored by the application, later being rendered in web pages without adequate sanitization or encoding. This vulnerability allows an attacker to inject malicious scripts into the user registration confirmation process, which are then executed in the browsers of users who view the affected pages. The exploitation vector typically involves an attacker submitting crafted input that is saved by the application and later displayed to other users or administrators. Because the vulnerability resides in the user registration confirmation functionality, it may be triggered during normal user onboarding workflows. The lack of a patch or mitigation at the time of reporting increases the risk of exploitation once an attacker discovers the vulnerability. Although no known exploits are currently reported in the wild, the medium severity rating indicates a moderate risk level. The vulnerability impacts confidentiality, integrity, and availability indirectly by enabling session hijacking, credential theft, or execution of unauthorized actions through the victim's browser context. The vulnerability does not require prior authentication, as it targets the registration confirmation process, which is generally accessible to unauthenticated users. User interaction is required in the sense that victims must visit the compromised page to trigger the malicious script execution. The absence of a CVSS score necessitates an independent severity assessment based on these factors.

For European organizations, this vulnerability poses a significant risk, especially for those relying on the Confirm User Registration plugin for managing user onboarding on public-facing websites or portals. Successful exploitation could lead to theft of user credentials, session tokens, or other sensitive information, potentially enabling unauthorized access to internal systems or user accounts. This could result in data breaches, reputational damage, and regulatory non-compliance, particularly under GDPR requirements concerning personal data protection. Additionally, attackers could leverage the vulnerability to perform phishing attacks or distribute malware via the affected web interface. Organizations in sectors such as finance, healthcare, and government are particularly vulnerable due to the sensitive nature of their data and the high value of their user accounts. The vulnerability's presence in a user registration context increases the attack surface, as it may be accessible to a wide range of users, including potential attackers. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits once the vulnerability details become widely known.

1. Immediate implementation of input validation and output encoding: Developers should ensure that all user-supplied input in the registration confirmation process is properly sanitized and encoded before storage and rendering. 2. Employ Content Security Policy (CSP): Organizations should deploy strict CSP headers to restrict the execution of unauthorized scripts and mitigate the impact of potential XSS attacks. 3. Monitor and audit user registration logs: Regularly review logs for suspicious input patterns or anomalous registration activities that could indicate exploitation attempts. 4. Limit the exposure of the registration confirmation page: Where possible, restrict access or implement CAPTCHA mechanisms to reduce automated or malicious submissions. 5. Update or patch the plugin promptly once a fix is released by the vendor. In the interim, consider disabling the Confirm User Registration plugin if feasible or replacing it with a more secure alternative. 6. Educate users and administrators about the risks of XSS and encourage cautious behavior when interacting with registration confirmation pages. 7. Implement Web Application Firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting this specific plugin.