Executive brief
The Bold Page Builder WordPress plugin used to create custom page layouts does not properly validate URLs in shortcodes, allowing contributors and above to inject malicious scripts. When a user clicks a crafted link in a published page, the malicious script executes in their browser, enabling attackers to steal session data, modify page content, or perform actions on behalf of the victim.
Technical details
The vulnerability is a stored cross-site scripting (XSS) flaw in the bt_bb_button, bt_bb_headline, and bt_bb_icon shortcode handlers. The plugin relies on a filter to validate link URLs before output in HTML attributes, but the filter can be evaded by embedding a literal tab character (0x09) between the JavaScript protocol scheme and the script keyword (e.g., java[TAB]script:). The browser's URL parser strips the tab during parsing, reassembling the javascript: scheme and executing the injected code. Attack requires Contributor role or above; no special configuration is needed. The vulnerability is fixed in version 5.9.8.
Affected products
- Bold Page Builder before 5.9.8
Timeline
- 2026-09-03: disclosed
- 2026-09-05: patched: Fixed in version 5.9.8