CVE-2026-13253
Received Received - Intake

Stored XSS in Ultimate Post WordPress Plugin

Publication date: 2026-07-09

Last updated on: 2026-07-09

Assigner: Wordfence

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.

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Meta Information

Published
2026-07-09
Last Modified
2026-07-09
Generated
2026-07-09
AI Q&A
2026-07-09
EPSS Evaluated
N/A
NVD
CVE-2026-13253
EUVD
EUVD-2026-42520

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
ultimate_post plugin to 5.0.31 (inc)

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

The Ultimate Post plugin for WordPress has a Stored Cross-Site Scripting (XSS) vulnerability in the 'moreResultsText' block attribute of the ultimate-post/advanced-search block in versions up to and including 5.0.31.

This vulnerability arises because the plugin does not properly sanitize and escape input: it uses wp_kses() which removes disallowed HTML tags but does not escape HTML special characters like double quotes. The attribute value is then directly inserted into an HTML attribute without proper escaping (esc_attr()).

As a result, authenticated users with contributor-level access or higher can inject malicious scripts that will execute whenever any user views the affected page.

Impact Analysis

This vulnerability can allow attackers with contributor-level access or above to inject arbitrary JavaScript code into pages.

When other users visit these pages, the injected scripts will execute in their browsers, potentially leading to session hijacking, defacement, or theft of sensitive information.

Because the attack requires authenticated access, it may be used to escalate privileges or compromise the integrity of the website content.

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