# WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN) <= 45.0 - Unauthenticated Missing Authorization to Graph Mailer Authorization Reset

- **ID:** WPSEC-2026-1258
- **Plugin:** WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN) (`wpo365-login`), https://wordpress.org/plugins/wpo365-login/
- **Affected versions:** all versions before 45.1
- **Fixed in:** 45.1 (Update to 45.1 or later.)
- **Severity:** Medium 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
- **Weakness:** CWE-862
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-10-20)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/wpo365-login
- **Fix released:** 2026-10-18
- **Published:** 2026-10-20
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1258/

## Description

The WPO365 plugin for WordPress is vulnerable to unauthorized modification of data in all versions up to, and including, 45.0, due to the mail authorization handler (Mail_Authorization_Helpers::authorize_mail_user) deleting the site's stored Graph Mailer authorization and cached application-level access token before the authorization response had been verified. This makes it possible for unauthenticated attackers to send a crafted mail authorization response, with any authorization code and a state that sets mode=mailAuthorize, that clears the existing delegated Microsoft Graph mail authorization. The site then cannot send email through the WPO365 Graph Mailer until an administrator authorizes it again.

## References

- https://wpsec.com/vuln/WPSEC-2026-1258/
- https://plugins.svn.wordpress.org/wpo365-login/tags/45.1/
- https://wordpress.org/plugins/wpo365-login/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1258/

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.