CVE-2026-13253 Details
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.
A stored cross-site scripting vulnerability has been identified in the Ultimate Post plugin for WordPress, specifically in versions through 5.0.31. The issue arises in the 'moreResultsText' block attribute of the 'ultimate-post/advanced-search' block. This vulnerability is due to inadequate input sanitization and output escaping in the 'Advanced_Search::content()' render callback. While the attribute value is filtered with 'wp_kses()' to remove disallowed HTML tags, it does not escape HTML special characters, such as double quotes, in plain text. Consequently, the unescaped data is directly added to the 'data-viewmoretext' HTML attribute without using 'esc_attr()'. As a result, authenticated attackers with contributor-level access or higher can inject arbitrary web scripts into pages, which will execute when a user accesses the compromised page.
Users are advised to update the Ultimate Post WordPress plugin to version 5.0.32 or later.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 9, 2026CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Ultimate Post | <= 5.0.31 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 9, 2026 | New CVE Received | [email protected] |