The BetterDocs - Knowledge Base Docs & FAQ Solution plugin for WordPress is vulnerable to stored cross-site scripting via the blockId attribute of the betterdocs/category-slate-layout Gutenberg block in versions up to and including 4.5.3. The root cause is insufficient input sanitization and lack of output escaping in the CategorySlateLayout::render() method, which directly inserts the blockId attribute into an HTML class attribute without using esc_attr(). This flaw allows authenticated attackers with contributor-level permissions or higher to inject arbitrary JavaScript that executes in the context of users viewing the injected pages.

An attacker with contributor-level access or higher can inject persistent malicious scripts into pages via the blockId attribute. These scripts execute in the browsers of users who visit the compromised pages, potentially leading to session hijacking, defacement, or other client-side attacks. The vulnerability does not affect availability but impacts confidentiality and integrity of user sessions and data.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict contributor-level access to trusted users only and consider disabling or limiting use of the affected Gutenberg block. Monitor official channels for updates from wpdevteam regarding patches or workarounds.