# Tainacan <= 1.3.0 - Authenticated (Editor+) PHP Object Injection via Metadata Order and Type Options

- **ID:** WPSEC-2026-0675
- **Plugin:** Tainacan (`tainacan`), https://wordpress.org/plugins/tainacan/
- **Affected versions:** all versions before 1.4.0
- **Fixed in:** 1.4.0 (Update to 1.4.0 or later.)
- **Severity:** High 7.2 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H)
- **Weakness:** CWE-502
- **Usage among sites WPSec scans:** plugin Low, affected versions Low (as of 2026-10-09)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/tainacan
- **Fix released:** 2026-10-07
- **Published:** 2026-10-08
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0675/

## Description

The Tainacan plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 1.3.0. This is due to deserialization of untrusted input from stored metadata order fields and filter/metadata type option values, which are passed to unserialize() without restricting allowed classes. This makes it possible for authenticated attackers with collection or metadata editing privileges (Editor-level access and above) to inject a PHP object through the REST API. No POP chain is known in the plugin itself, but if one is present through another plugin or theme on the site, an attacker may be able to delete arbitrary files, retrieve sensitive data or execute code.

## References

- https://wpsec.com/vuln/WPSEC-2026-0675/
- https://plugins.svn.wordpress.org/tainacan/tags/1.4.0/
- https://wordpress.org/plugins/tainacan/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0675/

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.