CVE-2024-3565 is a stored cross-site scripting vulnerability identified in the Content Blocks (Custom Post Widget) plugin for WordPress, affecting all versions up to and including 3.3.0. The vulnerability stems from insufficient sanitization and escaping of user-supplied input in the 'content_block' shortcode attributes. This flaw allows authenticated users with contributor-level access or higher to inject arbitrary JavaScript code into pages generated by the plugin. When other users access these pages, the injected scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, or unauthorized actions within the WordPress environment. The vulnerability is classified under CWE-79, which concerns improper neutralization of input during web page generation. The CVSS v3.1 base score is 6.4, reflecting a medium severity with network attack vector, low attack complexity, requiring privileges but no user interaction, and impacting confidentiality and integrity with a scope change. Although no public exploits have been reported yet, the vulnerability poses a significant risk due to the widespread use of WordPress and the plugin’s role in content management. The vulnerability’s exploitation requires an attacker to have at least contributor-level access, which is a moderate barrier but still feasible in many compromised or insider threat scenarios. The lack of output escaping and input sanitization indicates a coding oversight that can be remediated by applying proper validation and escaping techniques or updating to a patched version once available.

The primary impact of CVE-2024-3565 is the potential for stored cross-site scripting attacks within WordPress sites using the vulnerable Content Blocks plugin. Successful exploitation can lead to the execution of arbitrary JavaScript in the context of the victim’s browser, enabling attackers to steal session cookies, perform actions on behalf of users, deface content, or deliver further malware. This compromises the confidentiality and integrity of the affected sites and their users. Since the attack requires contributor-level privileges, the risk is elevated in environments where user accounts are less strictly controlled or where attackers have already gained partial access. The vulnerability does not directly affect availability but can indirectly disrupt operations through defacement or unauthorized changes. Organizations relying on this plugin for content management face reputational damage, potential data breaches, and loss of user trust if exploited. Given WordPress’s global market share and the plugin’s usage, the threat can affect a broad range of sectors including media, education, e-commerce, and government websites.

To mitigate CVE-2024-3565, organizations should immediately audit their WordPress installations for the presence of the Content Blocks (Custom Post Widget) plugin and verify the version in use. If possible, update the plugin to a version that addresses this vulnerability once released by the vendor. In the absence of an official patch, implement strict input validation and output escaping on all user-supplied shortcode attributes within the plugin code. Restrict contributor-level permissions to trusted users only and review user roles to minimize the number of users with such privileges. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious script injection attempts targeting the shortcode parameters. Regularly monitor logs for unusual activities indicative of XSS exploitation. Additionally, educate content contributors about safe content practices and the risks of injecting untrusted code. Conduct periodic security assessments and penetration tests focusing on plugin vulnerabilities and privilege escalation paths within WordPress environments.