The Content Blocks (Custom Post Widget) plugin for WordPress suffers from a stored cross-site scripting vulnerability (CWE-79) due to improper neutralization of input during web page generation. This occurs in the content_block shortcode, where user-created content blocks are not properly sanitized or escaped. Authenticated attackers with contributor or higher privileges can inject arbitrary JavaScript that executes in the context of users viewing the compromised content. This vulnerability affects all versions up to and including 3.3.9. The CVSS 3.1 base score is 6.4 (medium), with network attack vector, low attack complexity, privileges required at the contributor level, no user interaction needed, and impacts confidentiality and integrity with no availability impact. No patch or official remediation is currently documented.

Successful exploitation allows an authenticated contributor-level attacker to inject persistent malicious scripts into pages rendered by the plugin. These scripts execute in the browsers of users who view the infected content, potentially leading to unauthorized actions such as session hijacking or data theft. The confidentiality and integrity of user data may be compromised, but availability is not affected. There are no known active exploits reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, limit contributor-level access to trusted users only. Consider disabling or removing the Content Blocks (Custom Post Widget) plugin if possible to prevent exploitation. Monitor official vendor channels for updates regarding patches or mitigations.