# MPG <= 4.2.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'base-url' Shortcode Attribute

- **ID:** WPSEC-2026-0860
- **Plugin:** MPG – Multiple Page Generator, Bulk Landing Pages & Programmatic SEO (`multiple-pages-generator-by-porthas`), https://wordpress.org/plugins/multiple-pages-generator-by-porthas/
- **Affected versions:** all versions before 4.2.5
- **Fixed in:** 4.2.5 (Update to 4.2.5 or later.)
- **Severity:** Medium 6.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Low, affected versions None seen (as of 2026-10-13)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/multiple-pages-generator-by-porthas
- **Fix released:** 2026-10-13
- **Published:** 2026-10-14
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0860/

## Description

The MPG – Multiple Page Generator, Bulk Landing Pages & Programmatic SEO plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'base-url' attribute of the plugin's [mpg] and [mpg_match] shortcodes in all versions up to, and including, 4.2.4, due to insufficient input sanitization and output escaping. The attribute is HTML-entity-decoded and then put, without escaping, in front of each generated page URL that replaces the {{mpg_url}} placeholder in the shortcode's rendered content. 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.

## References

- https://wpsec.com/vuln/WPSEC-2026-0860/
- https://plugins.svn.wordpress.org/multiple-pages-generator-by-porthas/tags/4.2.5/
- https://wordpress.org/plugins/multiple-pages-generator-by-porthas/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0860/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.