Vulnerability · Published Oct 10, 2026 · Assigned by Wordfence
CVE-2026-96840Post Grid Gutenberg Blocks <= 5.1.0 - Unauthenticated Stored Cross-Site Scripting via display_name User Field
High 7.2
In plain English
A high-severity cross-site scripting in Post Grid Gutenberg Blocks – PostX from wpxpo. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official description
The Post Grid Gutenberg Blocks – PostX plugin for WordPress is vulnerable to Stored Cross-Site Scripting via display_name User Field in all versions up to, and including, 5.1.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. WordPress core's pre_user_display_name filter encodes &, <, and > but leaves double-quotes intact (ENT_NOQUOTES), allowing a Subscriber-level user to store a double-quote in their display_name via /wp-admin/profile.php that subsequently breaks out of the alt="" attribute at Archive_Title.php:144.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| wpxpo | Post Grid Gutenberg Blocks – PostX | 0 – through 5.1.0 |
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
References
- https://www.wordfence.com/threat-intel/vulnerabilities/id/39472e87-174c-4abf-bc83-fed0939440af?source=cve
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.41/addons/builder/blocks/Archive_Title.php#L144
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.41/addons/builder/blocks/Archive_Title.php#L98
- https://wordpress.org/plugins/ultimate-post/
- https://plugins.trac.wordpress.org/changeset/3727209/ultimate-post/trunk/addons/builder/blocks/Archive_Title.php