CVE-2025-11376 identifies a stored cross-site scripting vulnerability in the Colibri Page Builder plugin for WordPress, specifically in the handling of the 'colibri_loop' shortcode. The root cause is insufficient sanitization and escaping of user-supplied attributes, allowing authenticated users with contributor-level permissions or higher to inject arbitrary JavaScript code into pages. This malicious code is stored persistently and executed in the browsers of any users who visit the affected pages, potentially compromising session tokens, redirecting users to malicious sites, or performing unauthorized actions on behalf of users. The vulnerability affects all versions up to and including 1.0.335. The CVSS 3.1 base score is 6.4, reflecting a network attack vector with low attack complexity, requiring privileges but no user interaction, and impacting confidentiality and integrity with a scope change. No patches or known exploits are currently documented, but the vulnerability is publicly disclosed. The flaw arises from improper neutralization of input during web page generation (CWE-79), a common and dangerous web security issue. The attack requires an authenticated user with contributor or higher access, which means attackers must first compromise or have legitimate access to an account with these privileges. Once exploited, the injected scripts can affect all users viewing the compromised content, including administrators and visitors, potentially leading to broader compromise of the WordPress site or user data.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of their WordPress-based websites, especially those that rely on the Colibri Page Builder plugin. Attackers with contributor-level access can leverage this flaw to execute persistent XSS attacks, potentially hijacking sessions of administrators or other users, defacing websites, or injecting malware. This can lead to reputational damage, data breaches involving personal or sensitive information, and disruption of services. Organizations in sectors such as e-commerce, government, education, and media, which often use WordPress for public-facing sites, are particularly vulnerable. The medium severity rating reflects that while exploitation requires some level of access, the impact on confidentiality and integrity is notable, and the scope extends beyond the attacker to all users viewing the injected content. Given the widespread use of WordPress in Europe and the common practice of collaborative content management, the risk of exploitation is non-trivial. Additionally, failure to remediate may lead to compliance issues under GDPR if personal data is compromised via this vulnerability.

European organizations should take immediate steps to mitigate this vulnerability. First, monitor for and apply any official patches or updates released by extendthemes for the Colibri Page Builder plugin as soon as they become available. Until a patch is released, restrict contributor-level access to trusted users only and review existing user privileges to minimize the number of accounts that can exploit this vulnerability. Implement web application firewalls (WAFs) with rules designed to detect and block XSS payloads targeting the 'colibri_loop' shortcode. Employ Content Security Policy (CSP) headers to limit the execution of unauthorized scripts on affected sites. Conduct regular security audits and scanning of WordPress plugins to detect malicious code injections. Educate content contributors about secure input practices and monitor logs for suspicious activity. Additionally, consider temporarily disabling the shortcode or the plugin if feasible, or replacing it with a more secure alternative until the vulnerability is resolved. Backup website data regularly to enable recovery in case of compromise.