# Co-Authors Plus <= 4.2.1 - Authenticated (Contributor+) Guest Author Spoofing via Post Meta

- **ID:** WPSEC-2026-2744
- **Plugin:** Co-Authors Plus (`co-authors-plus`), https://wordpress.org/plugins/co-authors-plus/
- **Affected versions:** all versions before 4.2.2
- **Fixed in:** 4.2.2 (Update to 4.2.2 or later.)
- **Severity:** Medium 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N)
- **Weakness:** CWE-345
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-11-08)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/co-authors-plus
- **Fix released:** 2026-11-07
- **Published:** 2026-11-08
- **URL:** https://wpsec.com/vuln/WPSEC-2026-2744/

## Description

The Co-Authors Plus plugin for WordPress is vulnerable to guest author spoofing via 'cap-' prefixed custom fields in all versions up to, and including, 4.2.1, due to the guest author lookups by user_login, linked_account and user_email, and the linked-account list, querying post meta without limiting the results to the guest-author post type. This makes it possible for authenticated attackers with Contributor-level access and above to add 'cap-' custom fields to a post they can edit so that it is treated as a guest author profile. For example, a 'cap-linked_account' value naming another user makes the attacker-controlled display name, bio and website appear in that user's byline across the site.

## References

- https://wpsec.com/vuln/WPSEC-2026-2744/
- https://plugins.svn.wordpress.org/co-authors-plus/tags/4.2.2/
- https://wordpress.org/plugins/co-authors-plus/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-2744/

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.