CVE-2026-13253: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in wpxpo Post Grid Gutenberg Blocks – PostX
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.
AI Analysis
Technical Summary
CVE-2026-13253 is a stored Cross-Site Scripting vulnerability in the Ultimate Post WordPress plugin's Post Grid Gutenberg Blocks – PostX, affecting versions <=5.0.31. The vulnerability exists because the 'moreResultsText' block attribute is filtered with wp_kses(), which removes disallowed HTML tags but does not escape HTML special characters such as double quotes. The filtered input is then directly concatenated into an HTML attribute without using esc_attr(), enabling injection of arbitrary scripts by authenticated users with contributor-level permissions or higher. This can lead to script execution in the context of users viewing the injected content.
Potential Impact
An attacker with contributor-level access or higher can exploit this vulnerability to inject arbitrary JavaScript code that executes in the browsers of users who view the compromised pages. This can lead to theft of user credentials, session hijacking, or other malicious actions within the context of the affected site. The vulnerability does not affect availability but impacts confidentiality and integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict contributor-level access to trusted users only. Review and sanitize input for the 'moreResultsText' attribute manually if possible. Monitor official channels for updates or patches addressing this vulnerability.
CVE-2026-13253: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in wpxpo Post Grid Gutenberg Blocks – PostX
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.
CVSS v3.1
Score 6.4medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-13253 is a stored Cross-Site Scripting vulnerability in the Ultimate Post WordPress plugin's Post Grid Gutenberg Blocks – PostX, affecting versions <=5.0.31. The vulnerability exists because the 'moreResultsText' block attribute is filtered with wp_kses(), which removes disallowed HTML tags but does not escape HTML special characters such as double quotes. The filtered input is then directly concatenated into an HTML attribute without using esc_attr(), enabling injection of arbitrary scripts by authenticated users with contributor-level permissions or higher. This can lead to script execution in the context of users viewing the injected content.
Potential Impact
An attacker with contributor-level access or higher can exploit this vulnerability to inject arbitrary JavaScript code that executes in the browsers of users who view the compromised pages. This can lead to theft of user credentials, session hijacking, or other malicious actions within the context of the affected site. The vulnerability does not affect availability but impacts confidentiality and integrity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict contributor-level access to trusted users only. Review and sanitize input for the 'moreResultsText' attribute manually if possible. Monitor official channels for updates or patches addressing this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-06-24T19:53:28.879Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4f598768715ace43f21931
Added to database: 07/09/2026, 08:19:19 UTC
Last enriched: 07/16/2026, 10:00:07 UTC
Last updated: 08/23/2026, 10:52:06 UTC
Views: 48
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