CVE-2026-96840
Received Received - Intake

Stored XSS in Post Grid Gutenberg Blocks – PostX WordPress Plugin

Publication date: 2026-10-10

Last updated on: 2026-10-10

Assigner: Wordfence

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.

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Meta Information

Published
2026-10-10
Last Modified
2026-10-10
Generated
2026-10-10
AI Q&A
2026-10-10
EPSS Evaluated
N/A
NVD
CVE-2026-96840
EUVD
EUVD-2026-96224

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
wpxpo Post Grid Gutenberg Blocks – PostX 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

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Executive Summary

This is a Stored Cross-Site Scripting (XSS) vulnerability in the Post Grid Gutenberg Blocks – PostX WordPress plugin. It allows unauthenticated attackers to inject malicious scripts into web pages by exploiting insufficient input sanitization and output escaping in the display_name user field. The injected scripts execute when users access the affected pages.

Detection Guidance

Check WordPress user profiles for unusual display names containing double quotes or script tags. Inspect pages using PostX blocks for unexpected script execution in alt attributes. Review server logs for unauthorized script injections in post content.

Impact Analysis

An attacker could steal user sessions, deface websites, or redirect users to malicious sites. Since the vulnerability allows script injection without authentication, it poses risks to all visitors of an affected site, including potential data theft or unauthorized actions on their behalf.

Compliance Impact

This vulnerability could lead to unauthorized access to user data, violating GDPR's data protection principles and HIPAA's security requirements. If exploited, it may result in data breaches, triggering compliance violations and potential legal penalties for organizations handling sensitive user information.

Mitigation Strategies

Update the Post Grid Gutenberg Blocks – PostX plugin to the latest version. Remove any suspicious display names containing scripts or double quotes from user profiles. Implement WordPress core security hardening by enabling strict input validation and output escaping.

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