WordPress security changelog
MEDIUM CVE-2026-13253 Deferred

Post Grid Gutenberg Blocks – PostX: Cross-site scripting

Post Grid Gutenberg Blocks – PostX is affected by cross-site scripting. Exploitation requires at least contributor-level access. Injected script can execute in the affected site's origin when the vulnerable output is viewed. The published affected range is <= 5.0.31.

CVE / CNA score 6.4 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
Post Grid Gutenberg Blocks – PostX
Plugin slug
ultimate-post
Affected
<= 5.0.31
Safe version
> 5.0.31
Published
Jul 09, 2026
Weakness
CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This CVE was published Jul 09, 2026 and is one of 16 known issues for this plugin.

What to do

Update, patch or deactivate.

Update Post Grid Gutenberg Blocks – PostX to a release after 5.0.31, or disable and remove it until a fixed version is available.

A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical 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.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References

Primary and upstream sources