Co-Authors Plus <= 4.2.0 - Authenticated (Contributor+) Improper Authorization to Guest-Authored Post Editing via Username Collision
- ID
- WPSEC-2026-2531
- Plugin
- Co-Authors Plus (co-authors-plus)
- Affected
- from 3.0 before 4.2.1
- Remediation
- Update to 4.2.1 or later.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
- Weakness
- CWE-863
- Usage
- Plugin Medium · Affected versions Medium among sites WPSec scans, 2026-11-04
- Attack surface
- Co-Authors Plus on WPSec AttackSurface
- Fix released
- Published
Description
The Co-Authors Plus plugin for WordPress is vulnerable to Improper Authorization via the co-author capability mapping in all versions up to, and including, 4.2.0, due to the is_coauthor_for_post() function treating a registered user as a co-author whenever their user_login matches the user_login of a guest author bylined on the post, even when that guest author is not linked to the user. This makes it possible for authenticated attackers, with Contributor-level access and above, whose username matches an unlinked guest author's login, to be treated as a co-author of that guest author's posts and to view and edit posts they could not otherwise access, such as drafts and pending posts.
References
- https://wpsec.com/vuln/WPSEC-2026-2531/
- https://plugins.svn.wordpress.org/co-authors-plus/tags/4.2.1/
- https://wordpress.org/plugins/co-authors-plus/
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