CVE-2024-11463 is a reflected Cross-Site Scripting (XSS) vulnerability identified in the DeBounce Email Validator plugin for WordPress, affecting all versions up to and including 5.6.5. The vulnerability stems from improper neutralization of input during web page generation (CWE-79), specifically in the handling of the 'from', 'to', and 'key' HTTP parameters. These parameters are not sufficiently sanitized or escaped before being reflected in the web page output, enabling an attacker to inject arbitrary JavaScript code. Because the plugin is used within WordPress environments, which are widely deployed for websites globally, this vulnerability can be exploited remotely without authentication. The attacker must convince a user to click a maliciously crafted URL containing the payload in one of the vulnerable parameters. Upon visiting the link, the injected script executes in the context of the victim's browser, potentially allowing session hijacking, credential theft, or unauthorized actions within the user's session. The CVSS v3.1 score of 6.1 indicates a medium severity, with an attack vector over the network, low attack complexity, no privileges required, but requiring user interaction. The scope is changed (S:C) because the vulnerability affects components beyond the vulnerable plugin itself, potentially impacting the entire WordPress site. Currently, there are no known exploits in the wild, but the vulnerability is publicly disclosed and should be addressed promptly. No official patches have been linked yet, so mitigation may require temporary workarounds or disabling the plugin until an update is available.

The primary impact of this vulnerability is the potential compromise of user confidentiality and integrity through the execution of arbitrary scripts in the victim's browser. Attackers can steal session cookies, perform actions on behalf of authenticated users, or redirect users to malicious sites. For organizations, this can lead to account compromise, data leakage, defacement, or reputational damage. Since the vulnerability is exploitable without authentication and remotely, it poses a significant risk to any WordPress site using the affected plugin. The lack of availability impact reduces the risk of service disruption, but the integrity and confidentiality risks remain substantial. Organizations handling sensitive user data or providing critical services via WordPress are particularly vulnerable. The medium CVSS score reflects these factors, but the widespread use of WordPress and the plugin increases the potential attack surface globally.

Organizations should immediately assess their WordPress installations for the presence of the DeBounce Email Validator plugin and its version. Until an official patch is released, consider disabling or uninstalling the plugin to eliminate the attack vector. If disabling is not feasible, implement Web Application Firewall (WAF) rules to detect and block suspicious requests containing script tags or unusual payloads in the 'from', 'to', and 'key' parameters. Employ Content Security Policy (CSP) headers to restrict script execution sources and reduce the impact of injected scripts. Educate users about phishing risks to reduce the likelihood of clicking malicious links. Monitor web server logs for unusual parameter values and potential exploitation attempts. Once a patch is available, apply it promptly and verify the fix. Additionally, review and harden other plugins and themes to minimize overall XSS risks.