# Top 10 <= 4.5.2 - Authenticated (Contributor+) Stored Cross-Site Scripting via Popular Posts Block 'instance_id' Attribute

- **ID:** WPSEC-2026-1040
- **Plugin:** WebberZone Top 10 — Popular Posts (`top-10`), https://wordpress.org/plugins/top-10/
- **Affected versions:** all versions before 4.5.3
- **Fixed in:** 4.5.3 (Update to 4.5.3 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 Medium, affected versions Medium (as of 2026-10-15)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/top-10
- **Fix released:** 2026-10-14
- **Published:** 2026-10-15
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1040/

## Description

The WebberZone Top 10 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'instance_id' attribute of the Popular Posts block in all versions up to, and including, 4.5.2, due to insufficient input sanitization and output escaping when the value is used to build the class attribute of the popular posts wrapper div. 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-2026-1040/
- https://plugins.svn.wordpress.org/top-10/tags/4.5.3/
- https://wordpress.org/plugins/top-10/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1040/

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.