CVE-2025-2561 is a Stored Cross-Site Scripting (XSS) vulnerability identified in the Ninja Forms WordPress plugin prior to version 3.10.1. The root cause is the failure to properly sanitize and escape certain plugin settings, which allows high-privilege users, typically administrators, to inject malicious JavaScript code into the plugin’s stored data. This vulnerability is notable because it bypasses the usual WordPress security control that restricts unfiltered HTML capabilities, making it exploitable even in multisite environments where unfiltered_html is disallowed. The vulnerability requires an attacker to have high privileges (admin-level) and involves user interaction to trigger the malicious script execution. The CVSS 3.1 score is 4.8 (medium severity), reflecting that the attack vector is network-based with low attack complexity but requires high privileges and user interaction. The impact includes potential confidentiality and integrity loss, such as session hijacking, defacement, or unauthorized actions performed via the victim’s browser context. No public exploits have been reported yet, but the vulnerability is published and recognized by WPScan and CISA. Since Ninja Forms is a widely used WordPress plugin for form creation, this vulnerability poses a risk to websites relying on it for data collection and user interaction.

For European organizations, this vulnerability could lead to unauthorized script execution within administrative contexts, potentially allowing attackers to hijack sessions, manipulate form data, or perform unauthorized actions on affected WordPress sites. This can compromise sensitive user data collected via forms, damage organizational reputation, and disrupt business operations. Given that many European companies use WordPress for their websites and rely on plugins like Ninja Forms for customer interaction, the vulnerability could be leveraged to target administrative users, especially in multisite deployments common in larger enterprises or agencies. The confidentiality and integrity of data are primarily at risk, while availability impact is minimal. The medium severity rating reflects that exploitation requires high privileges, limiting the threat to insiders or compromised admin accounts, but the scope of affected systems is broad due to the popularity of WordPress and Ninja Forms.

European organizations should immediately update Ninja Forms to version 3.10.1 or later, where this vulnerability is fixed. Until patching is possible, restrict administrative access to trusted personnel only and enforce strong authentication mechanisms such as multi-factor authentication (MFA) to reduce the risk of privilege escalation or account compromise. Regularly audit user roles and permissions to ensure no unnecessary high-privilege accounts exist. Implement Content Security Policy (CSP) headers to mitigate the impact of potential XSS attacks by restricting script execution sources. Monitor WordPress logs and plugin activity for unusual behavior indicative of attempted exploitation. Additionally, consider isolating multisite environments and applying strict input validation on custom forms or plugin settings. Educate administrators about the risks of XSS and the importance of cautious input handling within the WordPress admin interface.