CVE-2026-13253

Post Grid Gutenberg Blocks for News, Magazines, Blog Websites <= 5.0.31 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'moreResultsText' Block Attribute

2026-07-08 18:16
Wordfence PRISM

Strategic Overview

Status
Patched in 5.0.32
Affected Plugin
Post Grid Gutenberg Blocks – PostX
Affected Version
<= 5.0.31
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-13253
View all Post Grid Gutenberg Blocks – PostX vulnerabilities

At a glance

CVE-2026-13253 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Post Grid Gutenberg Blocks WordPress plugin, affecting versions <= 5.0.31. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Contributor level or above. The issue is fixed in version 5.0.32; sites on affected versions should update now. Disclosed July 2026, reported by Wordfence PRISM.

Vulnerability Overview

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.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Post Grid Gutenberg Blocks <= 5.0.31 carries this weakness at moreResultsText, and reaching it takes an account at Contributor level or above. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Post Grid Gutenberg Blocks the fix is 5.0.32: builds <= 5.0.31 are affected, anything from 5.0.32 onward is not.

Remediation

Update to version 5.0.32, or a newer patched version

How does WordSec protect against this?

An attacker needs Contributor access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Post Grid Gutenberg Blocks 5.0.32 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-13253https://www.wordfence.com/threat-intel/vulnerabilities/id/070ccd70-22c3-47f1-9dce-a884bff9ea76https://nvd.nist.gov/vuln/detail/CVE-2026-13253

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C