CVE-2026-96840 Post Grid Gutenberg Blocks <= 5.1.0 - Unauthenticated Stored Cross-Site Scripting via display_name User Field
Unauthenticated attackers can inject arbitrary scripts via the display_name field, leading to stored XSS execution in the PostX WordPress plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-96840?
CVE-2026-96840 is a high-severity cross-site scripting vulnerability in wpxpo Post Grid Gutenberg Blocks – PostX, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-79
Which versions are affected by CVE-2026-96840?
How do I fix CVE-2026-96840?
No fix has been published for CVE-2026-96840 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-2026-96840 being exploited?
There is no known exploitation of CVE-2026-96840 in the wild and no public exploit code.
Sources
Also known as GHSA-8pf3-qx3w-w4jg.