CVE-2026-13253 Cross-site scripting in Post Grid Gutenberg Blocks – PostX
Authenticated contributors can inject arbitrary scripts via the moreResultsText attribute, leading to stored XSS execution on victim pages.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-13253?
CVE-2026-13253 is a medium-severity cross-site scripting vulnerability in wpxpo Post Grid Gutenberg Blocks – PostX, published on 9 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-13253?
How do I fix CVE-2026-13253?
No fix has been published for CVE-2026-13253 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-13253 being exploited?
There is no known exploitation of CVE-2026-13253 in the wild and no public exploit code.
Sources
Also known as GHSA-fmqh-3qcq-wcxg.