What the vulnerability does
01Description
The Ultimate Post plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'moreResultsText' block attribute of the ultimate-post/advanced-search block in versions up to and including 5.0.31. This is due to insufficient input sanitization and output escaping in the Advanced_Search::content() render callback: the attribute value is filtered with wp_kses(), which strips disallowed HTML tags but does NOT escape HTML special characters such as double quotes in plain text, and the result is then concatenated directly into the data-viewmoretext HTML attribute without esc_attr(). 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.
Explanation of Vulnerability in Simple Terms
02Summary
Post Grid Gutenberg Blocks – PostX versions up to 5.0.31 contain a stored cross-site scripting (XSS) vulnerability. An authenticated user with low privileges can inject malicious scripts that execute in the browsers of other site visitors, potentially compromising their sessions or stealing data. The vulnerability affects the block editor and has scope impact, meaning it can affect other users and components beyond the vulnerable plugin.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that run in other users' browsers when they view affected pages.
Potential impact on your site
04Site Impact
Visitors and admins viewing pages with the affected block may have their sessions hijacked or data stolen.
Conditions required to exploit
05Prerequisites
Attacker must have a low-privilege authenticated account (e.g., contributor or editor role).
Key dates
06Disclosure timeline
July 9, 2026
CVE published
July 9, 2026
Record updated
