Kubio AI Page Builder: Stored XSS through decoded copyright-block content
The Kubio AI Page Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via kubio/copyright Block Content in all versions up to, and including, 2.8.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This bypasses both the WordPress core kses-on-save filter and the plugin's own wp_kses_post() call, because entity-encoded script tags are treated as inert text by kses but are decoded into live HTML by the subsequent html_entity_decode() call in CopyrightBlock::render_template(). Entity decoding after HTML filtering reverses the protection; the export names the rendering function but not a dedicated request route. Affected versions reported by the CNA: <= 2.8.4.
- Component
- Kubio AI Page Builder
- Plugin slug
kubio- Affected
- <= 2.8.4
- Safe version
- See mitigation notes
- Published
- Sep 18, 2026
This CVE was published Sep 18, 2026 and is one of 11 known issues for this plugin.
Update, patch or deactivate.
This archive could not verify a fixed version from the official author release notes reviewed on 2026-10-13. Disable the affected feature or component where practical until remediation for the deployed configuration is established. Normalize/decode before applying the final HTML allowlist and escape the actual output context. Do not decode untrusted text into executable markup after sanitization; review existing copyright blocks. Official author release notes: https://wordpress.org/plugins/kubio/#developers.
No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical description
The Kubio AI Page Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via kubio/copyright Block Content in all versions up to, and including, 2.8.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This bypasses both the WordPress core kses-on-save filter and the plugin's own wp_kses_post() call, because entity-encoded script tags are treated as inert text by kses but are decoded into live HTML by the subsequent html_entity_decode() call in CopyrightBlock::render_template().
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N